Aim: To evaluate the incidental prostate cancer (PCa) rate and predictive factors in patients who underwent open prostatectomy (OP) with a pre-diagnosis of benign prostatic hyperplasia (BPH). Methods: This cross-sectional, retrospective study included patients with a pre-diagnosis of BPH, who underwent OP due to symptomatic prostate enlargement. Our database included age, medications, prostate-specific antigen (PSA), free/total PSA ratio, PSA density, digital rectal examination (DRE), prostate volume, serum neutrophil/lymphocyte ratio, platelet/lymphocyte ratio, aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio, presence of metabolic syndrome (MetS), and histopathological results after OP. Results: Of the 430 patients that underwent OP with a pre-diagnosis of BPH, 406 (94.4%) with a benign pathological diagnosis were evaluated as the benign group in and 24 (5.6%) detected to have PCa constituted the incidental PCa group. In the univariate analysis, age, AST/ALT ratio, MetS, and DRE significantly differed between the groups (p=0.008, p=0.005, p=0.004 and p<0.001, respectively). The rate of incidental PCa was much higher in the elderly patients. The cut-off value of age was 71.5 years in the PCa group according to the receiver operating characteristic curve analysis. According to the multivariate analysis, only DRE and presence of MetS were effective in predicting PCa. DRE was found 16 times more effective and MetS was 2.8 times more effective than the other parameters. Conclusion: Our results showed that DRE and presence of MetS can be useful predictive factors of incidental PCa in OP.