Staphylococcus epidermidis septicemia and pneumonia developed in an 18-year-old male undergoing bone marrow transplantation. The organism was isolated from multiple blood cultures, sputum cultures, an indwelling catheter tip and post-mortem lung biopsy specimens. The bacterium was resistant to penicillin, erythromycin, clindamycin, chloramphenicol, vancomycin, gentamicin, cephalothin and trimethoprim-sulfamethoxazole, but was sensitive to rifampin. The rapid demise of this patient, as well as the difficulty in achieving effective antibiotic therapy, illustrates the potential pathogenicity of this organism in immunosuppressed patients.