Our patient, we believe, experienced a primary HSV-2 infection manifested by fever, malaise, and orogenital mucocutaneous lesions. With resolution of systemic manifestations, and at a time of theorized rise in HSV-2 antibody levels, he had thrombocytopenic purpura which persisted for several weeks. An immune disorder secondary to HSV-2 infection similar to that of postrubella infection is postulated. If this theory is correct, severe immune thrombocytopenic purpura is yet one more of the many observed complications of HSV infection.