On the basis of a 12-year study of 58 patients at our medical center who had group A streptococcal bacteremia, we found that this disease is not uncommon when compared with other varieties of bacteremia. It occurs with about one-half of the frequency of bacteremias due to Klebsiella species and one-eighth of that of bacteremias due to Staphylococcus aureus. The infection is infrequently nosocomial (3.5% of cases) and the predominant causes are cutaneous or subcutaneous infections (72% of cases). While many patients are chronically ill, debilitated, or elderly, in our institution, as in some other public hospitals, the most important underlying condition is a history of iv drug abuse (28% of cases). Our data and those of some other recent publications suggest that the occurrence of cases related to iv drug abuse may be increasing. Intravenous drug abusers tend to be young adults, while other sources of infection are found more frequently in older patients. The frequent presence (10.3% of cases) of other organisms (especially S. aureus) in the blood of patients with group A streptococcal bacteremia has not been sufficiently emphasized in previous studies.