CIMMYT has invested a large and significant amount of public expenditures in wheat breeding research each year for several decades. Estimates of the impact of the wheat breeding program on wheat yield increases provides information to scientists, administrators, and policy makers regarding the efficacy and the rate of return to these investments, providing important information for future funding decisions. Using CIMMYT test plot data from the Yaqui Valley in Mexico from 1990-2002, regression results indicate that the release of modern CIMMYT varieties has contributed approximately 53.77 kg/ha to yield annually. The growing conditions of the experiment fields located in the Yaqui Valley approximate 40% of the developing world's wheat growing conditions. A rough estimate of the gains attributed to CIMMYT's wheat breeding program on a global scale is 304 million (2002) USD annually during the period 1990-2002. CIMMYT's total wheat breeding cost in 2002 was approximately 6 million dollars, making the benefit cost ratio approximately 50 to 1.