We undertook a phase I trial using fixed-dose cisplatin, escalating doses of etoposide, and reinfusion of previously obtained autologous bone marrow in 29 relapsed or refractory small cell and non-small-cell lung cancer patients. Median age was 59 years (range of 38-68 years). Three patients had small-cell and 26 patients had non-small-cell lung cancer. Patients received i.v. cisplatin 200 mg/m2 over 5 days and i.v. etoposide 600 mg/m2/day for 3 days (total of 1,800 mg/m2) that was escalated to 800, 1,000, 1,200, 1,400, and 1,600 mg/m2/day for 3 days (total of 2,400-4,800 mg/m2). Cryopreserved autologous bone marrow was thawed and reinfused through a central venous catheter the second day after the completion of chemotherapy. Toxicities included nausea, vomiting, alopecia, high-tone hearing loss, mucositis, diarrhea, renal insufficiency, metabolic acidosis, and severe myelosuppression. The duration of neutropenia (less than 500 neutrophils/microliter) ranged from 5 to 22 days (median of 11 days) and the duration of severe thrombocytopenia (platelets of less than 20,000/microliters untransfused) ranged from 2 to 19 days (median of 9 days). Reversible renal insufficiency (peak serum creatinines of 6.7, 6.6, 4.3, and 3.5 mg/dl) occurred in four patients who completed the therapy. In three patients, death occurred within 4 weeks of chemotherapy and marrow reinfusion. Three complete and 12 partial remissions (range of 1+(-)22+ months, median of 3 months) were observed. No response was noted in eight patients and tumor progression within 1 month of transplant occurred in two patients. The maximally tolerated dose of etoposide was 1,400 mg/m2/day (total of 4,200 mg/m2), since two of three patients developed life-threatening diarrhea at the 1,600 mg/m2/day (total of 4,800 mg/m2) dose. The encouraging antitumor effects of this regimen suggest that this approach may be useful therapy for lung cancer and other tumors sensitive to VP-16 and cisplatin.