Bacteremia caused by rapidly growing mycobacteria are usually due to Mycobacterium fortuitum or M. chelonei. Other rapidly growing mycobacteria generally are considered to be nonpathogenic. We report the case of a patient with bacteremia due to an unidentified, rapidly growing, scotochromogenic mycobacteria that was detected by a radiometric blood culture system. Results of in-vitro susceptibility testing indicated that the organism was susceptible to vancomycin and other antimicrobial agents, and the patient was successfully treated with vancomycin. We believe that this is the first report of successful use of vancomycin therapy for a mycobacterial infection.