Chlamydia and gonorrhea are the two most common bacterial sexually transmitted diseases (STDs) disproportionately affecting adolescents. Compared to other states, in 1997, Louisiana ranked fifth and seventh in reported case rates of gonorrhea and chlamydia, respectively. These two diseases can now be diagnosed with a urine test using DNA amplification technology, making it possible to identify asymptomatically infected persons without having to conduct a physical examination. In a school screening program piloted in Louisiana school-based health centers, all students in 12 urban public high schools were offered the urine test. Most infected students had no symptoms. The infection rate in girls was generally at least twice as high as among boys. Over time, the prevalence of chlamydia infection decreased. School-based screening is feasible and acceptable and can identify a large number of asymptomatic, infected youth. Screening programs which target asymptomatic youth should be expanded in order to reduce the burden of chlamydia and gonorrhea in our communities.