To clarify clinical significance of symptoms presented at the beginning of treatment, we analyzed the symptoms in 240 patients with non-small cell lung cancer treated with definitive radiation therapy. Symptoms were classified into four groups: no symptom (Grade 0), cough, sputum/hemosputum and fever up (Grade 1), chest pain and breathlessness (Grade 2), appetite loss, body weight loss, SVC syndrome, hoarseness, and pain in the upper limb/shoulder (superior sulcus tumor) (Grade 3), and their therapeutic outcomes were examined. The 2- and 5-year overall actuarial survival rates for patients with squamous cell carcinoma were 38.5% and 15.4% for Grade 0, 40.5% and 20.1% for Grade 1, 17.9% and 2.6% for Grade 2, and 15.8% and 5.3% for Grade 3. A statistical difference was noted in survival between Grades 0-1 and Grades 2-3 (P < 0.01), but was not seen between Grades 0 and 1, or between Grades 2 and 3. As for patients with stage III disease alone, the difference in survival was still significant between Grades 0-1 and 2-3 (P < 0.05). In patients with adenocarcinoma/large cell carcinoma, however, no obvious relationship was found between symptoms and prognosis, except for body weight/appetite loss. In conclusion, though the symptoms closely related to clinical stage and performance status and not an independent prognostic factor, chest pain and breathlessness correlated with poor therapeutic outcome as well as body weight loss and T3-4 related symptoms, while cough, sputum (hemosputum), and fever were favorable symptoms in patients with squamous cell carcinoma who received definitive radiation therapy.