In a 54-month retrospective review, we compared the clinical features of 26 narcotic addicts with staphylococcal endocarditis (group 1) and ten other addicts with nonstaphylococcal endocarditis (group 2). The admission temperature and the respiratory rate of patients in group 1 were significantly higher (P less thn .05 and less than .02 respectively) than those of patients in group 2. Group 1 also differed from group 2 in the following variables: (1) bilateral multiple pulmonary infiltrates in 46% vs none in group 2; (2) greater incidence of symptoms referable to the central nervous system (50% vs none in group 2); and (3) gastrointestinal symptoms of vomiting, diarrhea, or constipation in 62% vs 10% in group 2. Serious cardiovascular, renal, and other complications were more frequent in staphylococcal endocarditis. Tricuspid regurgitation occurred with equal frequency in both groups and was of no value in differentiating staphylococcal from nonstaphylococcal endocarditis.