We describe two HIV-seropositive patients with acute pneumococcal empyema and pericarditis. Cardiac tamponade evolved rapidly in each patient and was reversed with prompt surgical intervention. In each case, immunologic abnormalities were detected which could have facilitated local spread of infection and progression to tamponade. Pericarditis, an otherwise rare manifestation of pneumococcal infection in the antibiotic era, should be anticipated in HIV-seropositive patients with pneumococcal empyema.