OBJECTIVES: To describe the clinical features of Kaposi sarcoma (KS) in organ-allograft recipients and to determine the contribution of human herpesvirus 8 (HHV-8) investigations to the management of KS. DESIGN, SETTING, AND PATIENTS: We examined 20 organ-allograft recipients with KS at Pitié-Salpêtrière Hospital, Paris, France, between November 1, 1991, and May 31, 1999. METHODS: We detected HHV-8 antibodies using an indirect immunofluorescence assay and the HHV-8 DNA genome using nonnested polymerase chain reaction with KS-associated herpesvirus 330233 primers in peripheral blood mononuclear cells collected at transplantation and KS diagnosis. We detected the HHV-8 genome in involved and uninvolved tissue specimens and in 10 patients' serum samples collected 1 month before the first manifestation of KS. We determined the HHV-8 double-strand DNA sequence and subtypes of open reading frame 26. INTERVENTION: Management of KS consisted of progressively tapering immunosuppressive therapy regardless of KS dissemination. Associated infections were treated when possible. Chemotherapy was prescribed only when a functional disability persisted, and polychemotherapy was prescribed for life-threatening disease. MAIN OUTCOME MEASURES: Percentage of recipients with KS remission and stabilization, organ-graft survival, and death rates. RESULTS: Remission of KS was obtained in 9 (45%) of the 20 patients independently of disease dissemination, with a mean follow-up of 35 months. The kidney graft survived in 12 (67%) of the 18 patients. Only 1 patient (5%) died of KS progression. All allograft recipients had anti–HHV-8 antibodies before transplantation. We detected HHV-8 DNA in all involved tissue samples but not in serum samples 1 month before KS onset. The most prevalent subtype was HHV-8 C (9 [53%] of 17 patients) and was not associated with extradermatological extension of KS compared with subtypes A and B′. CONCLUSIONS: Virological investigations of HHV-8 contribute poorly to KS management. Prospective studies are needed to determine the role of HHV-8 virological investigations and to identify associated cofactors so as to prevent KS in organ-allograft recipients.Arch Dermatol.2000;136:1452-1458