The patient was an eight-year-old black male who presented to the Children's Hospital of Philadelphia (CHP) in June 1977 with foot pain. Abnormal findings on physical examination were diffuse shotty lymphadenopathy without hepatosplenomegaly. Examination of the extremities was normal. There was no evidence of increased bruising or bleeding. Laboratory data revealed a hemoglobin of 11.2 gm/dl, white blood cell count of 26,200/cu mm, and platelet count of 21,000/cu mm. Serum uric acid level was 4.2 mg/dl. The remainder of the laboratory findings were within normal limits. Bone marrow examination revealed a hypercellular marrow replaced with lymphoblasts. Immunologic evaluation showed these cells to have no surface immunoglobin and no rosette formation with sheep red blood cells. The patient received vincristine 1.5 mg/M2 daily, oral prednisone at 40 mg/M2 daily, L-asparaginase 6,000 IU/M2 for nine intramuscular doses, and methotrexate 12 mg intrathecally. After 28 days, bone marrow aspiration showed that the leukemia was in remission. He then received 2,400 rad cranial irradiation over three weeks, along with four more doses of intrathecal methotrexate, given once weekly. Maintenance consisted of monthly pulses of vincristine (1.5 mg/M2), prednisone (40 mg/M2 for five days), daily oral 6-mercaptopurine (75 mg/M2), and weekly oral methotrexate (20 mg/M2). After six months of maintenance, the patient was given a scheduled course of reinduction therapy with vincristine, prednisone, and L-asparaginase. Eleven months after diagnosis both testes were noted to be enlarged on physical examination. Wedge biopsy of both testes revealed leukemic infiltration. Examination of the bone marrow and cerebrospinal fluid (CSF) at that time were unremarkable. The patient was treated with vincristine, prednisone, and L-asparaginase again for four weeks and received intrathecal methotrexate as central-nervous-system (CNS) prophylaxis. Twenty-four hundred rad were given to both testes at 200 rad/day with decrease in testicular size. Maintenance consisted of monthly pulses of vincristine and prednisone with oral methotrexate and 6-mercaptopurine. Seven months after his testicular relapse the patient had a bone marrow relapse. He expired eight months later with disseminated leukemia.