HIV postexposure prophylaxis (PEP) is now a well-established part of the management of health care workers after occupational exposures to HIV. Use of PEP for adults exposed to HIV after sexual contact or injection drug use in nonoccupational settings remains controversial with limited data available. There is even less information available concerning HIV PEP for children and adolescents after accidental needlestick injuries or sexual assault. The objective was to describe the current practice of and associated problems with HIV PEP for children and adolescents at an urban academic pediatric emergency department. A retrospective review of all children and adolescents offered HIV PEP between June 1997-June 1998 was conducted. Ten pediatric and adolescent patients were offered HIV PEP, six patients after sexual assault, four patients after needle stick injuries. There were two small children 2 and 3 years of age and eight adolescents. Of these 10 patients, eight were started on HIV PEP. The regimens used for PEP varied; zidovudine, lamivudine, and indinavir were prescribed for in seven patients and zidovudine, lamivudine, and nelfinavir for one other. All 10 patients were HIV negative by serology at baseline testing and all available for follow-up testing (5 of 10) remained HIV negative at 4 to 28 weeks. Only two patients completed the full course of 4 weeks of antiretroviral therapy. Financial concerns, side effects, additional psychiatric and substance abuse issues as well as the degree of parental involvement influenced whether PEP and clinical follow-up was completed. HIV PEP in the nonoccupational setting for children and adolescents presents a medical and management challenge, and requires a coordinated effort at the initial presentation to the health care system and at follow-up. The difficulties encountered in the patients in our series need to be considered before initiating prophylaxis. A provisional management approach to HIV PEP in children and adolescents is proposed.