The proposed study is a single center (with multiple long-term YCFs) treatment trial of the CDC-recommended azithromycin regimen (1 gm PO once) for chlamydia in males. This study is designed primarily to determine the frequency of chlamydia treatment failure following azithromycin in males who do versus do not have urethral symptoms of urethral discharge and/or dysuria. Anticipated enrollment is 446 males, between the age of 12 to 21 years old, with subject participation duration of 28 days and study duration of 4 years. The primary objective of the study is to assess the microbiological efficacy of azithromycin in uncomplicated Chlamydia trachomatis infection in males with versus without urethral symptoms in YCFs.