During the past four years, an epidemic of Kaposi sarcoma pneumocystis carinii and other serious intercurrent infections has been diagnosed in previously healthy homosexual men. All patients have acquired defective cell mediated immunity, which may be of pathogenetic importance. Cytomegalovirus infection and nitrite sniffing are possible etiological factors. The patients have fever, generalized lymphadenopathy, loss of weight and intercurrent infections or Kaposi sarcoma. The mortality is high and no specific therapy is available, but some of the intercurrent infections may be amenable to treatment. Four cases of this syndrome have been seen in a Danish hospital within the past year. Three of them had never been in the US. Two of the patients were sexual partners. As this new disease has now reached Denmark, Danish physicians are informed about its existence.