Patients with solid tumor malignancies who failed extensive front-line treatments were treated with high-dose BCNU followed by autologous bone marrow transplantation. Since 1976, 14 patients were treated in this program with BCNU doses ranging from 600 to 1500 mg/m² over 2 days. Three patients developed pulmonary toxicity only few weeks after receiving high-dose BCNU at total doses of 900, 1000, and 1500 mg/m². Two of the three patients had had prior irradiation to the primary tumor. The third patient did not have prior irradiation to the chest but had received prior nitrosourea therapy. The use of high-dose BCNU in transplantation may be limited by early pulmonary toxicity.