Fifty-nine patients received 61 courses of cyclophosphamide, cisplatin, and carmustine combined. The phase I study consisted of seven dose escalations. Dose levels 5 and 6 also included the attempted addition of melphalan at 40 and 80 mg/m2. The maximum tolerated dose for the three-drug combination was 5620 mg/m2 of cyclophosphamide, 165 mg/m2 of cisplatin, and 600 mg/m2 of carmustine. The dose-limiting toxic effect was fatal veno-occlusive disease of the liver in two of five patients treated at the highest dose level. Veno-occlusive disease of the liver was fatal in two of 40 patients treated at Dose level 4, the maximum tolerated dose. The median time to recovery of polymorphonuclear leukocyte counts to greater than 500/microliters and platelet counts to transfusion independence greater than 20,000/microliters was 19 and 22 days, respectively, after marrow reinfusion. Other toxic effects observed included postdischarge pulmonary toxicity, which appeared to respond to prednisone therapy. Thus, this combination of alkylating agents can be combined at close to the transplant dose of each individual agent. The response rate was high despite considerable prior treatment in most patients. Of 16 evaluable patients with breast cancer, 15 responded (six complete responses). Of six evaluable patients with sarcoma, six responded (one complete response). While patients with melanoma had had no prior treatment, 11 of 17 patients responded (65%). There are currently three patients who are disease-free. Two patients with melanoma were rendered disease-free by excisional biopsy of the only remaining nodule after good partial response, and a patient with metastatic breast cancer remains disease-free after a complete response at 36+ months.