During the first week of March 1974, a hospitalized patient being evaluated for hyperproteinemia and hypertension experienced fever, chills, and myalgia and showed pulmonary signs consistent with diffuse pneumonia. Subsequently, the findings from serologic tests confirmed that the patient had viral influenza. Seven other compromised hosts on the same ward developed symptoms of pneumonic influenza, and serologic data on three of the seven confirmed influenza A2. Additionally, a previously healthy young adult admitted with acute respiratory distress died of nonbacterial complications and was shown to have community-acquired influenza. The unusual features of the epidemic were the intrahospital localization of the epidemic in compromised hosts, the high rate of pneumonic complications, the low rate of secondary bacterial infection, and the severity of the viral pneumonia in the community-acquired case.