Abstract Aim To prospectively assess the cardiopulmonary morbidity and quality of life in patients with non-small cell lung cancer (NSCLC) treated with postoperative radiotherapy (PORT) in comparison to those not receiving PORT. Materials and methods From 2003 to 2007, 291 patients entered the study; 171 pN2 patients received 3D-planned PORT (PORT group), 120 pN1 patients (non-PORT group) did not. One month after surgery, all patients completed EORTC QLQ C-30 questionnaire and had pulmonary function tests (PFT); cardiopulmonary symptoms were assessed by modified LENT-SOM scale. Two years later, disease-free patients repeated the same examinations. The differences between baseline values and values recorded at two years in QLQ, LENT-SOM and the PFT of the two groups were compared. Results In the whole cohort, the rate of non-cancer related deaths was 5.3% and 5.0% in PORT and non-PORT group, respectively. Ninety-five patients (47 – PORT group, 48 – non-PORT group) were included into the final analysis. The differences in the QLQ and cardiopulmonary function (LENT/SOM, PFT) between both groups were insignificant. The forced expiratory volume in one second was on average 12.2% and 1.3% better in the PORT and the non-PORT group, respectively, p=0.2. Conclusions Our findings support the hypothesis about insignificant morbidity of 3D-planned PORT.