Multi-modality treatment consisting of cisplatin, VP-16, and 5-fluorouracil chemotherapy given concomitantly with external beam radiation was used to treat 64 patients with locally advanced Stage III non-small cell lung carcinoma. This regimen was used in a preoperative fashion for four cycles in patients considered surgically resectable and with curative intent for six cycles in the remainder of patients. The clinical response rate for the entire group was 84% and the overall local control rate was 74%. The median survival was 13 months with a median follow-up for live patients of 19 months. The actuarial 3-year survival and disease-free survival rates were 30% and 23%, respectively. Histologic complete response was 39% and appeared to predict for survival. The 3-year actuarial survival and disease-free survival rates for 23 resected patients were 69% and 45%, respectively, with the complete histologic responders having a disease-free survival of 78%. The pattern of first recurrence did not appear to differ by histology or presence of lymph nodes in this subset of patients. The actuarial 3-year survival and disease-free survival rates for inoperable patients receiving six cycles of treatment were 18% and 23%, respectively. The local control was 67% with the majority of these patients having Stage IIIB disease. The Mountain International staging system appeared to predict for operability, local recurrence, and survival. This concomitant treatment regimen is feasible, with the major toxicities being leukopenia, nausea, and vomiting.