We investigated if high dose melphalan and total body irradiation could be administered to adult patients with acceptable toxicity. Nineteen adult patients with relapsed disease, 15 of them having hematologic malignancies, were treated with high-dose melphalan (100 mg/m2-140 mg/m2) divided over 2 consecutive days followed by a rest period of 4 days before receiving total body irradiation, 850 rad administered in five fractionated doses over 3 days. Subsequently 11 patients received autologous, seven allogeneic and one syngeneic, bone marrow transplantation. All patients had severe myelosuppression and the major extramedullary toxicity was mucositis. There were three early deaths, two related to septicemia and one to graft-versus-host disease with associated cytomegalovirus pneumonitis. All patients were heavily pretreated, and 16 were demonstrating progressive disease on alternative salvage therapies at the time of bone marrow transplantation. Two of the 16 evaluable patients (12.5%) achieved complete remissions, and 10 (63%) achieved partial remissions for a total response rate of 75%. One patient is a long-term disease-free survivor (over 1 yr). An occasional patient may be cured by this approach. The combination of melphalan, an alternative alkylating agent to cyclophosphamide and total body irradiation are associated with moderate gastrointestinal toxicity in heavily pretreated adult patients. The combination warrants further investigation in a less heavily pretreated population to determine more accurately the complete response rate.