ObjectivesTo assess the effectiveness of an intervention for providing information, and support to HIV-positive donors on changes in their sexual behavior, and to assess which donor characteristics are predictive of behavior change.DesignSubjects were randomly assigned to a structured intervention or community referral group. Follow-up assessments were conducted every 6 months.SettingNew York City, New York, USA.ParticipantsA cohort of 271 HIV-infected persons who donated blood to the New York Blood Center.InterventionDonors randomized to the structured intervention program met individually with a nurse for counseling, and were offered a six-session support group. The program was designed to provide information, encourage safer sexual behavior, and provide support.Main outcome measuresSexual behavior, psychological distress, and psychological help seeking, and immune function.ResultsIn both groups there was a large decrease over time in reports of unsafe sexual activity. However, more than 30% of participants in both groups reported unsafe sexual activity at the 1-year follow-up visit. Donors randomized to the structured intervention program did not report significantly more behavior change at the 1-year follow-up.ConclusionsBetter programs to promote behavior change in seropositive individuals are needed.