From January 1991 to November 1993, 110 patients with histologically confirmed stage IIIA and IIIB non-small cell lung cancer (NSCLC), were seen at our Institution. Our study was designed to evaluate whether redirection to surgery of otherwise unresectable patients may be obtained by preoperative therapy. Forty-nine patients were considered eligible for neoadjuvant treatment. Thirty-two (Group I) were treated with two or three cycles of cisplatin, vinblastine and mitomycin C and 17 (Group II) received two cycles of cisplatin, VP16, alpha 1 timosine and interferon. The overall response rate was 81.2% for Group I and 88.7% for Group II. Downstaging was predictive of resectability (P < 0.05). Forty-one patients (83.6%) underwent thoracotomy with 37 (75.5%) radical resections. Conservative techniques (bronchovascular reconstruction) (22 cases) were preferred over pneumonectomy (2 cases). The resectability rate was 84% for Group I and 87% for Group II (P = NS). Treatment-related complications were minor, with no deaths. Postoperative complications occurred in two cases in each group (7.4% and 14.3%). There was no histologic evidence of tumor in three patients. Two-year survival was 75% for Group I and 55% for Group II (P = NS). To date 35 patients who had complete resection are alive, and free of disease. We conclude that preoperative chemotherapy produces high response and resectability rates in both stage IIIA and IIIB unresectable NSCLC; radical resection using a conservative technique is possible in patients who are otherwise unresectable; no local recurrence occurred after radical resection; no significant differences were demonstrated between the two protocols.