Abstract: Objective: To assess the response of three dimensional conformal radiotherapy (3D-CRT) on non- small cell lung cancer (NSCLC). Methods: A total of 200 NS CLC patients were treated with the 3D- CRT, which was given every other day and 5 to 8Gy per fraction with the total doses from 48 to 72Gy. All cases were followed- up in 6 to 42 months, with average of 24 months. Results: Total survival rates of one, two and three year for the entire group was 69.0%, 48.0% and 36.5%, respectively. All the patients were reexamined in 3 months after treatment, mass disappeared in 98 patients,shrink over 50% in 91 patients and the other cases didn't shrink as half as before. The overall response rate (CR+PR) was 100% for the primary tumor. Conclusion: The 3D- CRT is well tolerated in most patients with lung cancer and has produced a good responses. Further follow- up will be needed for confirmation of the long- term effect.