Prostatic melanosis is a rare lesion characterized by melanocytic proliferation in the prostatic epithelium and stroma. This entity is absolutely benign and it is not a precursor for malignant melanoma. Yet, the pathogenesis of prostatic melanosis is not fully elucidated. Differential diagnosis of melanosis with primary and metastatic malignant melanoma is crucial because of the clinical manifestation and their biological nature differentiation. Here, we have presented a 67-year-old man who was diagnosed with prostatic melanosis with prostatic adenocarcinoma, and differential diagnosis with melanocytic lesions has been discussed.