OBJECTIVES: To prospectively measure the uptake of Herpes simplex virus Type 2 (HSV-2) testing and psychosocial response to a new serologic diagnosis of HSV-2 in a health maintenance organization (HMO) population. STUDY DESIGN: Randomly selected urban HMO enrollees were invited to be tested for HSV-2 antibody at a research clinic. Participants had blood drawn and completed demographic and psychosocial questionnaires. RESULTS: Of 3111 eligible enrollees contacted, 344 (11%) were tested. Eighty-seven (26%) tested HSV-2 seropositive, and 44 (51%) of these did not report a prior genital herpes diagnosis. Distress, measured by the total mood disturbance, was 6.5 points higher on average following a new genital herpes diagnosis relative to baseline (actual range = 109 points, P = 0.003) but not statistically different from HSV-2 negative or previously diagnosed participants. CONCLUSIONS: HMO enrollees unexpectedly testing HSV-2 positive showed short-term psychosocial distress that resolved during 6-month follow-up. Findings suggest that concerns about psychosocial burden should not deter voluntary serologic HSV-2 testing in primary care settings.