Stage has been defined as the major prognostic factor in resected non-small cell lung cancer (NSCLC). However, there is some evidence that indicates season of operation could play a role in the survival of patients. Between January 1995 and June 2008, 698 (621 men and 77 women) patients who had undergone pulmonary resection for NSCLC were evaluated. Patients were analysed according to surgical-pathological stages and month of the year in which they were operated. Vitamin D receptor (VDR) polymorphism was also analysed in 62 patients. The median survival time in all patients was 60 +/- 6 months (95% confidence interval (CI): 44-81 months). The survival of patients who underwent resection in winter was statistically significantly shorter than those operated in summer (P = 0.03). When patients were analysed according to T, N and season, resection time of the year was calculated to be an independent determinant of survival (P = 0.04). A VDR genotype was also associated with better prognosis (P = 0.04). Season of the operation, VDR polymorphism and N status seemed to have independent effects on survival of operated NSCLC patients.