Prognostic value of p21WAF1/CIP1 expression in non-small-cell lung cancer patients (NSCLC) remains unclear. In this study the authors investigated the clinical significance of p21WAF1/CIP1 expression in a group of 117 NSCLC patients, who underwent curative pulmonary resection. Expression of p21WAF1/CIP1 protein was assessed immunohistochemically and samples showing>5% of positive tumor cells were considered positive. Seventy-six samples (65%) showed positive nuclear p21WAF1/CIP1 protein expression. There was no relationship between the expression of p21WAF1/CIP1 protein and major clinico-pathological factors, and neither there was an impact of p21WAF1/CIP1 protein expression on disease-free and overall survival. p21WAF1/CIP1 protein occurrence was not correlated with previously determined p53 protein expression and there was also no relationship between all possible p21WAF1/CIP1/p53 phenotypes and survival. In uni- and multivariate analysis only stage of disease was independent prognostic factors. These results suggest the lack of prognostic relevance of p21WAF1/CIP1 expression (analyzed separately or jointly with p53 protein) in surgically treated NSCLC patients.