This review focuses on the diagnosis and treatment of common sexually transmitted diseases (STDs) encountered among adolescents in the U.S. and other developed countries. Included are new recommendations for the treatment of primary and recurrent genital herpes, management of pelvic inflammatory disease, and a revised approach to the care of adolescent victims of sexual assault. Diagnosis begins with a classification based on major clinical findings: genital ulcers with lymphadenitis, urethritis, vaginal discharge, pelvic inflammatory disease, and male STD syndromes. Appropriate laboratory evaluation for each of these clinical presentations is detailed and treatment options are summarized. Preventive interventions along with suggestions for an approach to the preadolescent well care visit, generally scheduled at age 11ñ12 years, are offered. Routine preventive therapy after a sexual assault takes into account difficulty in follow-up and the need to reassure adolescents and their families that all prophylaxis for possible infection has been provided.