Oral hairy leukoplakia was initially reported only in HIV-infected patients and was considered pathognomonic for HIV infection. The presence of Epstein-Barr virus and the decrease in Langerhans cells seem to be necessary for the development of oral hairy leukoplakia. HIV antigen is not present in oral hairy leukoplakia. We report on seven renal transplant recipients with oral hairy leukoplakia. In six of these patients no HIV infection was present. All patients showed marked immunosuppression following a vigorous immunosuppressive regimen. Five patients each had several rejection episodes, which were treated with further immunosuppressive therapy in addition to the basic immunosuppressive regimen. One patient was infected with HIV from the renal graft and another suffered from liver cirrhosis with portal hypertension caused by chronic hepatitis B infection. We believe that oral hairy leukoplakia is a marker for severe immunosuppression that is not necessarily associated with HIV infection. Organ transplant recipients undergoing dermatological check-up should be examined for oral hairy leukoplakia.