In a retrospective analysis of 150 incompletely resected NSCLC patients treated with adjuvant external beam radiotherapy 32 (21.3%) survived 3 years with no symptoms of disease. Ipsilateral mediastinal/hilar lymph node involvement and macroscopic incomplete surgery were the prognostic factors that unfavourably influenced survival in Cox's proportional hazards model. Postoperative external beam radiotherapy was the efficient adjuvant treatment method in microscopically incompletely resected NSCLC, predominantly with no nodes involvement, but had no benefit in those with macroscopic incomplete surgery.