All male detainees at the Chicago jail were offered chlamydia and gonorrhea screening before April 2003, when there was a change to testing only symptomatic men. The following year, the number of reported male jail cases declined by 92% for chlamydia and 91% for gonorrhea, which resulted in a 33% decline in the total reported chlamydia cases among men in Chicago and a 20% decline in total reported gonorrhea among men. Discontinuation of male chlamydia/gonorrhea screening at a large jail resulted in a missed opportunity to screen a high-risk population, and resulted in substantial declines in reported morbidity.