['Colorectal cancer screening beginning at age 50 is recommended for all Americans considered at average risk for the development of colorectal cancer regardless of gender or race/ethnicity. We determined the influence of gender and race/ethnicity on the cost-effectiveness of recommended colorectal cancer screening regimens.', 'We determined age-specific colorectal cancer incidence rates; the proportion of left-sided cancers; and the proportion of localized cancers in Asian, black, Latino and white men and women using the California Cancer Registry. We incorporated these data and available data for life expectancy and colorectal cancer survival to model the cost-effectiveness of two 35-year colorectal cancer-screening interventions.', 'Age-specific colorectal cancer incidence rates were highest in black men and lowest in Latino women. Screening beginning at age 50 was most cost-effective in black men and least cost-effective in Latino women (measured as dollars spent per year of life saved) using annual fecal occult blood testing combined with flexible sigmoidoscopy every five years and using colonoscopy every 10 years. The cost-effectiveness of a 35-year screening program in black men beginning at age 45 was similar to the cost-effectiveness of screening white men and black women beginning at age 50 and more cost-effective than screening nonblack women as well as Asian and Latino men beginning at age 50.'] Do gender and race/ethnicity affect the cost-effectiveness of colorectal cancer screening?