This is a report of an outbreak and subsequent course of a highly infectious epidemic disease which occurred at Ardmore Air Force Base, Okla., in the fall of 1955. The disease is characterized by upper respiratory infection, prolonged malaise, generalized adenopathy, painful hepatosplenomegaly, and a pronounced tendency to relapse into a chronic smouldering illness of several months' duration. The clinical course superficially resembled that of infectious mononucleosis or infectious hepatitis, with some aspects reminiscent of epidemic pleurodynia. All of these diagnoses were considered originally but later rejected in view of the clinical course of over 100 patients. The notable differentiating points were the absence of jaundice, consistently negative heterophil agglutinations, and the absence of atypical lymphocytes. We believe that this syndrome represents a clinical entity which, in sporadic form, may go unrecognized or be erroneously diagnosed as infectious mononucleosis or anicteric hepatitis. It is referred to as "Ardmore disease" since