Fifteen patients with Stage IV lung cancer both untreated and previously treated were enrolled into a high-dose chemotherapy program with multiple alkylating agents and autologous bone marrow reinfusion. Eight patients received cyclophosphamide at 7.5 gm/m2 over 3 days with thiotepa escalated from levels of 1.8 mg/kg to 6.0 mg/kg over 3 days. Seven patients received the above dose of cyclophosphamide plus thiotepa at 675 mg/m2 and oral melphalan escalated from levels of 0.75 mg/kg to 2.5 mg/kg over 3 days. Both regimens are part of larger Phase I-II clinical studies. The median time to recovery of more than 500 granulocytes and more than 50,000 platelets per microliter was 16 and 27 days, respectively. Two patients died as a consequence of severe, overwhelming infections during their period of aplasia. Of the 13 evaluable patients, no patients achieved a complete response and seven patients (47%) obtained a partial response. The median duration of response was 12 weeks. Other nonhematologic toxicities included nausea/vomiting, diarrhea, mucositis, skin rash, hemorrhagic cystitis, and cardiomyopathy. Since there are substantial toxicities associated with high-dose chemotherapy and responses of such brief duration, further investigation with these drug combinations is not warranted.