Background and Purpose: Up to now, evidence about survival of patients with non-small-cell lung cancer treated with radiation therapy alone is only available from clinical studies. The authors analyzed survival experience depending on several prognostic factors from a population-based cancer registry and compared this to survival data from the literature. Patients and Methods: Between April 1996 and September 1999, 1,696 patients with lung cancer were recruited by the Halle Lung Cancer (HALLUCA) Study. 1,183 patients were diagnosed as having non-small-cell lung cancer, and 188 in clinical stages I-IIIb (15.9%) were treated with radiation therapy alone. Results: The median survival time of all patients was 10.2 months, the 2-year overall survival rate amounted to 15.8%. Besides tumor stage, radiation dose was found to be a statistically significant prognostic factor for survival in univariate analysis. The median survival time was 4.2 months for 66 patients treated with < 50 Gy, 10.7 months for 80 patients treated with 50 to < 60 Gy, and 18.9 months for 42 patients treated with ≥ 60 Gy; the corresponding 2-year overall survival rates were 8.7%, 13.4%, und 35.2%. The significant influence of dose persisted even after adjustment for different confounders in a Cox regression model. Conclusion: Patients treated with 50 to < 60 Gy under a potentially curative therapeutic regimen had a significantly lower survival, compared to patients treated with ≥ 60 Gy. In terms of quality assurance, the large proportion of patients treated with radiation doses below the curative range of ≥ 60 Gy was unexpected.