PURPOSE: The effect of dose escalation of up to 6500 cGy on local control and survival was investigated in locally advanced non-small cell lung cancer. MATERIALS AND METHODS: Ninety eight patients with biopsy-proven unresectable non-small cell lung cancer without distant metastases or medically inoperable patients with lower-stage were treated with definitive radiotherapy alone. Group A were treated by thoracic irradiation, 6000 cGy or less in total tumor dose with daily fractions of 180 to 200 cGy: and group B was treated with 6500 cGy of same daily fractions. RESULTS: The actuarial overall survival rate for the entire group was 54% at 1 year, 26.6% at 2 years and 16.4% at 3 years with a median survival time of 13 months. Statistically significant prognostic factors that affect survival rate were stage and N-stage. However, no improvement in local control and survival has been seen with higher dose radiotherapy(group B). CONCLUSION: Dose escalation of up to 6500 cGy was no effect on local control and survival rate. To increase the survival rate of non-small cell lung cancer hyperfractionated radiotherapy or concurrent chemoradiotherapy should be considered.