Over an 18-month period, the incidence of group A beta-hemolytic streptococcal bacteremia rose from an average of 2.5 per 10,000 patient discharges to 17.9. A retrospective analysis was performed comparing patients with group A beta-hemolytic streptococcal bacteremia during this 18-month period with those who presented over the preceding 36 months. Most of the increased incidence was attributable to individuals hospitalized with a diagnosis of drug addiction who had concomitant soft-tissue infection, although the absolute number of hospitalized drug addicts did not change during this interval. No common or distinctive group A streptococcal serotypic patterns were discovered. This experience suggests that group A beta-hemolytic streptococcal bacteremia and soft-tissue infection may present in epidemic fashion among parenteral drug addicts in the absence of a common source.