<?xml version="1.0" encoding="us-ascii"?><InstanceReport xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><Version>2.4.0.8</Version><ReportLongName>107 - Disclosure - BASIS OF PRESENTATION</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><CurrencyCode /><FootnoteIndexer /><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><MCU><KeyName /><CurrencySymbol /><contextRef><ContextID>cx_01_June_2012_TO_31_May_2013</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0001409430</EntityValue><PeriodDisplayName /><PeriodType>duration</PeriodType><PeriodStartDate>2012-06-01T00:00:00</PeriodStartDate><PeriodEndDate>2013-05-31T00:00:00</PeriodEndDate><Segments /><Scenarios /></contextRef><UPS /><CurrencyCode /><OriginalCurrencyCode /></MCU><CurrencySymbol /><Labels><Label Key="CalendarSupplement" Id="0" Label="12 Months Ended" /><Label Key="Calendar" Id="1" Label="May 31, 2013" /></Labels></Column></Columns><Rows><Row FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>4</Level><ElementName>us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="cx_01_June_2012_TO_31_May_2013" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>&lt;p align="justify" style="font-family: times new roman,times,serif; font-size: 10pt;"&gt;
      &lt;b&gt;NOTE 1 &amp;#8211; BASIS OF PRESENTATION&lt;/b&gt;
    &lt;/p&gt;
    &lt;table border="0" cellpadding="0" cellspacing="0" style="border-color: black; font-size: 10pt; border-collapse: collapse; font-family: times new roman,times,serif;" width="100%"&gt;
        &lt;tr&gt;
          &lt;td valign="top" width="5%"&gt;a)&lt;/td&gt;
          &lt;td&gt;
            &lt;p align="justify" style="font-family: times new roman,times,serif; font-size: 10pt;margin:inherit;"&gt;
              &lt;b&gt;Organization&lt;/b&gt;
            &lt;/p&gt;
          &lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
          &lt;td&gt;&amp;#160;&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
          &lt;td&gt;
            &lt;p align="justify" style="font-family: times new roman,times,serif; font-size: 10pt;margin:inherit;"&gt;Osprey Ventures, Inc. was incorporated in the state of Wyoming on May 17, 2006, and changed its name to All American Gold Corp. (the &amp;#8220;Company&amp;#8221;) on October 15, 2010, to engage in the acquisition, exploration and development of mineral resource properties. The Company is considered an exploration stage company as it has not generated revenues from its operations.&lt;/p&gt;
          &lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
          &lt;td&gt;&amp;#160;&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td valign="top" width="5%"&gt;b)&lt;/td&gt;
          &lt;td&gt;
            &lt;p align="justify" style="font-family: times new roman,times,serif; font-size: 10pt;margin:inherit;"&gt;
              &lt;b&gt;Going Concern&lt;/b&gt;
            &lt;/p&gt;
          &lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
          &lt;td&gt;&amp;#160;&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
          &lt;td&gt;
            &lt;p align="justify" style="font-family: times new roman,times,serif; font-size: 10pt;margin:inherit;"&gt;These financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America with the assumption that the Company will be able to realize its assets and discharge its liabilities in the normal course of business rather than through a process of forced liquidation.&lt;/p&gt;
          &lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
          &lt;td&gt;&amp;#160;&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
          &lt;td&gt;
            &lt;p align="justify" style="font-family: times new roman,times,serif; font-size: 10pt;margin:inherit;"&gt;The Company&amp;#8217;s significant operating losses raise substantial doubt about its ability to continue as a going concern. Inherent in the Company&amp;#8217;s business are various risks and uncertainties, including its limited operating history, historical operating losses, dependence upon strategic alliances, and the historical success rate of mineral exploration.&lt;/p&gt;
          &lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
          &lt;td&gt;&amp;#160;&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
          &lt;td&gt;
            &lt;p align="justify" style="font-family: times new roman,times,serif; font-size: 10pt;margin:inherit;"&gt;
              In the accompanying financial statements, the Company incurred an accumulated deficit of $2,259,721
              for the period from May 17, 2006 (inception), to May 31, 2013, and has no revenue. The Company&amp;#8217;s future success is primarily dependent upon the existence of gold or other precious minerals on properties for which the Company owns a working interest or an option to acquire an interest. No minerals have yet been discovered on the properties. The Company&amp;#8217;s success will also be dependent upon its ability to raise sufficient capital to fund its exploration programs and, if gold is discovered, to exploit the discovery on a timely and cost-effective basis.
            &lt;/p&gt;
          &lt;/td&gt;
        &lt;/tr&gt;
    &lt;/table&gt;</NonNumbericText><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>nonnum:textBlockItemType</ElementDataType><SimpleDataType>na</SimpleDataType><ElementDefenition>The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 810

 -SubTopic 10

 -Section 50

 -Paragraph 8

 -URI http://asc.fasb.org/extlink&amp;oid=28200181&amp;loc=SL6228881-111685



Reference 2: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 720

 -SubTopic 15

 -URI http://asc.fasb.org/subtopic&amp;trid=2122524



Reference 3: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 205

 -SubTopic 10

 -Section 50

 -Paragraph 1

 -URI http://asc.fasb.org/extlink&amp;oid=6359566&amp;loc=d3e326-107755



Reference 4: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 235

 -SubTopic 10

 -Section 50

 -Paragraph 3

 -URI http://asc.fasb.org/extlink&amp;oid=6367646&amp;loc=d3e18780-107790



Reference 5: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 205

 -SubTopic 10

 -Section 45

 -Paragraph 3

 -URI http://asc.fasb.org/extlink&amp;oid=7668296&amp;loc=d3e288-107754



Reference 6: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 810

 -SubTopic 10

 -URI http://asc.fasb.org/subtopic&amp;trid=2197480



Reference 7: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 810

 -SubTopic 10

 -Section 50

 -Paragraph 1

 -URI http://asc.fasb.org/extlink&amp;oid=18733093&amp;loc=d3e5614-111684



Reference 8: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 915

 -SubTopic 235

 -Section 50

 -Paragraph 1

 -URI http://asc.fasb.org/extlink&amp;oid=6472506&amp;loc=d3e38932-110933



Reference 9: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 852

 -SubTopic 10

 -URI http://asc.fasb.org/subtopic&amp;trid=2209116



Reference 10: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 272

 -SubTopic 10

 -Section 50

 -Paragraph 3

 -URI http://asc.fasb.org/extlink&amp;oid=6373374&amp;loc=d3e70478-108055



Reference 11: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 275

 -SubTopic 10

 -URI http://asc.fasb.org/subtopic&amp;trid=2134480



Reference 12: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 205

 -SubTopic 10

 -URI http://asc.fasb.org/subtopic&amp;trid=2122150



</ElementReferences><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>BASIS OF PRESENTATION [Text Block]</Label></Row></Rows><Footnotes /><IsEquityReport>false</IsEquityReport><ReportName>BASIS OF PRESENTATION</ReportName><MonetaryRoundingLevel>UnKnown</MonetaryRoundingLevel><SharesRoundingLevel>UnKnown</SharesRoundingLevel><PerShareRoundingLevel>UnKnown</PerShareRoundingLevel><ExchangeRateRoundingLevel>UnKnown</ExchangeRateRoundingLevel><HasCustomUnits>true</HasCustomUnits><IsEmbedReport>false</IsEmbedReport><IsMultiCurrency>false</IsMultiCurrency><ReportType>Sheet</ReportType><RoleURI>http://www.allamericangoldcorp.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock</RoleURI><NumberOfCols>1</NumberOfCols><NumberOfRows>1</NumberOfRows></InstanceReport>
