The total number of cases of heroin-induced endocarditis occurring over a four-year period were reviewed in order to explain an increase in the number of cases in the last year studied (1975). Brown heroin was noted to be used more frequently by addicts during the period of increased incidence. Cultures of "street samples" of brown and white heroin as well as cocaine were obtained in order to elucidate a possible relationship between the increased use of brown heroin and the increased number of endocarditis cases. Despite frequent contamination of both white and brown heroin, none of the common endocarditis-causing pathogens were isolated from the samples. Staphylococcus aureus, the most common etiological agent, frequently resulted in tricuspid endocarditis. That the accepted criteria for tricuspid endocarditis may be present without actual cardiac valve involvement is demonstrated by a most unusual case of hepatic vasculature infection.