EXHIBIT (j)

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in this Post-Effective Amendment No. 50 to Registration Statement No. 33-39242 on Form N-1A of our reports dated January 27, 2010 relating to the financial statements and financial highlights of American Century World Mutual Funds, Inc., including Emerging Markets Fund, Global Growth Fund, International Discovery Fund, International Growth Fund, International Opportunities Fund, International Stock Fund, International Value Fund, NT Emerging Markets Fund and NT International Growth Fund, appearing in the Annual Report on Form N-CSR of American Century World Mutual Funds, Inc. for the year ended November 30, 2009, and to the references to us under the headings “Financial Highlights” in the Prospectuses, and “Independent Registered Public Accounting Firm” and “Financial Statements” in the Statement of Additional Information, which are parts of such Registration Statement.

/s/ DELOITTE & TOUCHE LLP                                

DELOITTE & TOUCHE LLP

Kansas City, Missouri

February 4, 2010