The aim of the study was to assess the frequency of serum Ab-anti-p53 in 39 patients with advanced NSCLC and to evaluate the predictive value of the test. Antibodies were present in 10 (25.6%) of patients. There was no correlation between Ab-anti-p53 and clinical characteristics including age, gender, and histological type of tumor. In 17 patients response to chemotherapy (CT) was obtained (in one patient--complete, and in 16--partial response). The percentage of patients responding to CT in group with and without serum antibodies did not differ significantly (33% and 48%, respectively; p = 0.48). The results of the study indicate that serum Ab-anti-p53 are relatively often present in advanced NSCLC patients, however the clinical value of this test needs further evaluation.