BACKGROUND፡ Trichomoniasis is a sexually transmitted infectious disease caused by a flagellated protozoa, Trichomonas vaginalis (T.vaginalis) and is often asymptomatic in men. Benign prostatic hyperplasia (BPH) and prostate cancer (PCA) are the most common urological diseases in the elderly. Scientists have proposed various factors which trigger prostate cancer, including sexually transmitted diseases. Thus, this study aimed to evaluate the potential role of T. vaginalis as a risk factor for various prostate lesions such as hyperplasia and prostate cancer.METHODS: A total of 250 paraffin-embedded of different prostate lesion biopsies were analyzed by Polymerase Chain Reaction (PCR) using the beta-tubulin gene for identifying T. vaginalis.RESULT: All 250 pathologic specimens were negative for this parasite by using PCR technique.CONCLUSION: It seems that T. vaginalis may have not had a causative role for different prostate lesions and it seems proposed PCR technique is an insufficient method to find the parasite in paraffin-embedded tissues. Therefore, other diagnostic techniques to identify the parasite in biopsy samples are suggested.