This study aimed to investigate the relationship between clinicopathological factors and plasma brain natriuretic peptide (BNP) levels in non-small cell lung cancer (NSCLC) patients. A total of 133 patients with advanced NSCLC were included in this study. The level of BNP was determined at the time of diagnosis. The BNP plasma concentration was measured using a chemiluminescent enzyme immunoassay kit. The univariate relationship between each independent clinicopathological variable and plasma BNP was examined using the Chi-square test. The survival curves were determined using the Kaplan-Meier method. According to the cut-off value of plasma BNP levels (11.5 and 22.4 pg/ml), plasma BNP negatively correlated with the presence of metastases (Chi-square test, p=0.0374 and p=0.0098, respectively). However, no significant association between patient survival time and plasma BNP levels was found. Reduced plasma BNP levels in advanced NSCLC patients with metastases were noted and the possibility was raised that BNP decreases distant metastases of advanced NSCLC patients.