A 38-year-old male farm worker with relapsing acute lymphoblastic leukemia spontaneously developed an ulcerating ulcer on his anterior thigh which was surrounded by a non-tender area of erythema. Bacillus cereus was isolated from the ulcer and blood, and the patient received intravenous penicillin and vancomycin for one week. When sensitivity studies were returned he was treated with gatifloxacin orally. After two weeks of combined antimicrobial therapy and negative blood cultures, the patient received combination chemotherapy with vincristine, prednisone, doxorubicin and cyclophosphamide. He was hospitalized a day after completing chemotherapy with neutropenic sepsis due to B. cereus. He received similar antimicrobial therapy as previously, but died three days later. At autopsy, the patient was found to have acute mitral valve endocarditis and bilateral brain abscesses. This was the first case of B. cereus endocarditis reported in a patient with acute lymphoblastic leukemia.