Nin one binding protein (NOB) 1 has been reported to be involved in cancer. However, the role of NOB1 in prostate cancer (PCa) has yet to be elucidated. The present study aimed to investigate the clinical role of NOB1 in PCa. The gene and protein expression levels of NOB1 were detected using quantitative polymerase chain reaction and western blot analysis in fresh samples of PCa and matched adjacent noncancerous tissues (n=32). NOB1 expression was also assessed using immunohistochemistry in a large number of patients with PCa (n=456) and paired adjacent noncancerous tissues between December 2003 and December 2010. The association between NOB1 expression and clinicopathological features and prognosis was investigated. The expression of NOB1 was found to be higher in the fresh samples of PCa than in the paired adjacent noncancerous tissues at the gene and protein levels. Immunohistochemistry revealed that the positive expression rates of NOB1 in PCa and the paired adjacent noncancerous tissues were 53% (242/456) and 6.1% (28/456), respectively. NOB1 expression was significantly correlated with Gleason score (P<0.001) and distant metastasis (P<0.001). Furthermore, patients with PCa with positive NOB1 expression had lower overall survival and recurrence‑free survival (RFS) compared with those with negative NOB1 expression. Multivariate analysis showed that NOB1 was an independent marker of RFS (hazard ratio, 3.45; 95% confidence interval, 1.41‑6.35; P=0.006). These findings suggest that NOB1 may be a potential prognostic indicator for PCa.