The first report on the administration of the chemoprotective agent Ethyol (amifostine) in conjunction with high dose carboplatin to a patient in the pediatric/adolescent age group is presented. A 17 year old teenager with recurrent cerebellar medulloblastoma received a total of five courses of high dose carboplatin 2 x 600 mg/m2 (1200 mg/m2 total) in each cycle. A complete response has been observed following the third treatment cycle. However, cumulative grade IV hematological toxicity developed following each of the first four treatments. Therefore, the fifth treatment was administered in conjunction with amifostine, at a dose of 2 x 740 mg/m2. Time to complete hematological recovery (Hb > 100 g/l, granulocytes > 2.0 G/l, platelets > 100 G/l) was 52, 58, 72, 78 and 50 days, respectively, following treatments nos 1, 2,,3, 4 and 5. The duration of grade III-IV neutropenia (< 1.0 G/l) was 3, 7, 8, 10 and 5 days, respectively. The duration of grade II-IV thrombocytopenia (platelets < 75 G/l) was 10, 25, 35, 40 and 32 days, respectively. Grade IV thrombocytopenia (platelets < 25 G/l) lasted for 5, 10, 12, 18 and 3 days, respectively, after each consecutive treatment. The total number of platelet transfusions was 1, 2, 2, 3 and 1, with the transfusion of 6, 9, 11, 11 and 5 units of platelets. The administration of amifostine has not been accompanied by any serious side effect. A short decrease in body temperature and a transient drop of blood pressure have been observed. Although hematological toxicity of high dose carboplatin has not been eliminated by amifostine, we conclude that significant protection was achieved in this situation of progressive bone marrow exhaustion.