BACKGROUNDProstate cancer is the most frequent malignancy among men nowadays.METHODSImmunohistochemical expression of prostate-specific antigen (PSA) was retrospectively investigated in 10 patients admitted with clinical suspicion of the prostate cancer. Slides were collected from archived biopsiesandthey were stained for PSA.The final reaction product was evaluated as negative (0), weak/moderate positive (1), and intense positive (2).RESULTSGlandular prostate carcinoma was found in 40% (n=4) and undifferentiated carcinoma in 60% (n=6). The immunoreaction for PSA was intense positive in 30% (n=3), weak/moderate positive in 50% (n=5) and negative in 20% (n=2) of total cases.CONCLUSIONSWe concludethat PSA immunoreaction is helpful for the differential diagnosis based on our results.