Note 1 - Basis of Presentation	9 Months Ended
Sep. 30, 2011
Significant Accounting Policies [Text Block]	1. Basis of Presentation — The accompanying unaudited condensed consolidated financial statements have been prepared by Monolithic Power Systems, Inc. (the “Company” or “MPS”) in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) have been condensed or omitted in accordance with these rules and regulations. The information in this report should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto included in its Form 10-K filed with the SEC on March 4, 2011. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments (consisting only of normal recurring adjustments) necessary to present fairly the Company’s financial position, results of operations and cash flows for the interim periods presented. The financial statements contained in this Form 10-Q are not necessarily indicative of the results that may be expected for the year ending December 31, 2011 or for any other future period. Recent Accounting Pronouncements In April 2011, the Financial Accounting Standards Board (FASB) issued authoritative guidance that results in common principles and requirements for measuring and disclosing fair value, which apply to all reporting entities that are required or permitted to measure or disclose the fair value of an asset, a liability, or an instrument classified in a reporting entity’s shareholders’ equity in the financial statements. Some of the amendments clarify the FASB’s intent about the application of existing fair value measurement requirements. Other amendments change a particular principle or requirement for measuring fair value or for disclosing information about fair value measurements. This guidance is to be applied prospectively. For public entities, this guidance is effective during interim and annual periods beginning on or after December 15, 2011. Early application is not permitted. The Company does not expect this new guidance to have a significant impact on the Company’s consolidated financial statements. In June 2011, the FASB issued authoritative guidance to improve the comparability, consistency, and transparency of financial reporting and to increase the prominence of items reported in other comprehensive income. Under this guidance, an entity has the option to present the total of comprehensive income, the components of net income, and the components of other comprehensive income either in a single continuous statement of comprehensive income or in two separate but consecutive statements. The guidance is to be applied retrospectively. For public entities, this guidance is effective for fiscal years, and interim periods within those years, beginning on or after December 15, 2011. Early application is permitted.

Note 1 - Basis of Presentation

9 Months Ended

Sep. 30, 2011

Significant Accounting Policies [Text Block]

1. Basis of Presentation — The accompanying unaudited condensed consolidated financial statements have been prepared by Monolithic Power Systems, Inc. (the “Company” or “MPS”) in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) have been condensed or omitted in accordance with these rules and regulations. The information in this report should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto included in its Form 10-K filed with the SEC on March 4, 2011.

In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments (consisting only of normal recurring adjustments) necessary to present fairly the Company’s financial position, results of operations and cash flows for the interim periods presented. The financial statements contained in this Form 10-Q are not necessarily indicative of the results that may be expected for the year ending December 31, 2011 or for any other future period.

Recent Accounting Pronouncements

In April 2011, the Financial Accounting Standards Board (FASB) issued authoritative guidance that results in common principles and requirements for measuring and disclosing fair value, which apply to all reporting entities that are required or permitted to measure or disclose the fair value of an asset, a liability, or an instrument classified in a reporting entity’s shareholders’ equity in the financial statements. Some of the amendments clarify the FASB’s intent about the application of existing fair value measurement requirements. Other amendments change a particular principle or requirement for measuring fair value or for disclosing information about fair value measurements. This guidance is to be applied prospectively. For public entities, this guidance is effective during interim and annual periods beginning on or after December 15, 2011. Early application is not permitted. The Company does not expect this new guidance to have a significant impact on the Company’s consolidated financial statements.

In June 2011, the FASB issued authoritative guidance to improve the comparability, consistency, and transparency of financial reporting and to increase the prominence of items reported in other comprehensive income. Under this guidance, an entity has the option to present the total of comprehensive income, the components of net income, and the components of other comprehensive income either in a single continuous statement of comprehensive income or in two separate but consecutive statements. The guidance is to be applied retrospectively. For public entities, this guidance is effective for fiscal years, and interim periods within those years, beginning on or after December 15, 2011. Early application is permitted.