Since Jan. 1991 a prospective randomized study for Stage III unresectable non small cell lung cancer(NSCLC) has been conducted to evaluate the response rate and tolerance of induction chemotherapy with MVP followed by hyperfractionated radiotherapy and evaluate the efficacy of maintenance chemotherapy in Asan Medical Center. All patients in this study were treated with hypefractionated radiotherapy (120 cGy/fx BID, 0480 cGy/54 fx) following 3 cycles of induction chemotherapy, MVP (Mitomycin C 6 mg/m2, Vinblastin B mg/ m2, Cisplatin 60 Mg/ m2) and then the partial and complete responders from induction chemotherapy were randomized to 3 cycles of adjuvant MVP chemotherapy group and observation group. 48 patients were registered to this study until December 1992; among 48 patients 3 refused further treatment after induction chemotherapy and 6 received incomplete radiation therapy because of patient's refusal, 39 completed planned therapy. Twenty-three(58%) patients including 2 complete responders showed response from induction chemotherapy. Among the 21 patients who achieved a partial response after induction chemotherapy, 1 patient rendered complete clearance of disease and 10 patients showed further regression of tumor following hypefractionated radiotherapy. Remaining 10 patients showed stable disease or progression after radiotherapy. Of the sixteen patients judged to have stable disease or progression after induction chemotherapy, seven showed more than partial remission after radiotherapy but nine showed no response in spite of radiotherapy. Of the 35 patients who completed induction chemotherapy and radiotherapy, 25 patients(64%) including 3 complete responders showed more than partial remission. Nineteen patients were randomized after radiotherapy. Nine patients were allocated to adjuvant chemotherapy group and 4/9 shewed further regression of tumor after adjuvant chemotherapy. For the time being, there is no suggestion of a difference between the adjuvant chemotherapy group and observation group in distant metastasis rate and survival. Median survival time was 13 months. Actuarial survival rates at 6, 12 and 18 months of 39 patients who completed this study were 84.6%, 53.7% and 40.3%, respectively. The partial and complete responders from induction chemotherapy showed significantly bettor survival than non-responders(p=0.028). Incidence of radiation pneumonitis in this stuffy group was less than that in historical control group inspite of induction chemotherapy. All patients tolerated hyperfractionated radiotherapy without definite increase of acute complications compared with conventional radiotherapy group. The longer fellow up is needed to evaluate the efficacies of induction and maintenance chemotherapy and survival advantage by hypefractionated radiotherapy but authors are encouraged with an excellent tolerance, higher response rate and improvement of one year survival rate in patients of this study.