Twenty-four patients with a variety of malignant diseases (13 lymphoma, 4 myeloma, 1 ALL, 6 solid tumours) were treated with the alkylating agents busulphan and melphalan as a preparative regimen for autologous BMT. Thirteen males and 11 females, aged 27-53 years (median 39.5 years) received oral busulphan 1 mg/kg q6 h on days -6 to -3, followed by i.v. melphalan 140 mg/m2 on day -2 and infusion of cryopreserved haemopoietic cells on day 0. The major toxicity seen was gastrointestinal with nausea, vomiting and diarrhoea in 17 patients and severe mucositis in 22. There was no evidence of cardiotoxicity, nephrotoxicity, haemorrhagic cystitis or clinical signs of hepatic veno-occlusive disease. Twenty-three patients engrafted with the median duration of neutropenia (< 0.05 x 10(9)/l) 10 days (range 5-63 days) and thrombocytopenia (< 50 x 10(9)/l) 43 days (range 5-350 days). Three patients died of transplant-related complications. Of 15 evaluable patients with active disease at BMT, 9 responded and 6 were refractory. Sixteen evaluable patients were in CR after BMT. Seven relapsed, 1 died in remission and 8 remain in CR 12-46 months (median 29 months) later. Of the group of 13 lymphomas, overall and relapse-free actuarial survival at 36 months was 64% and 58%, respectively, while for the entire group of 24 patients these values were 39% and 34%. Busulphan and melphalan is a safe and inexpensive conditioning regimen for autologous BMT with acceptable toxicity and substantial antitumour activity particularly against lymphomas.