Prostatitis syndromes are frequent and cause pain and discomfort in adult males. Non bacterial types occur more often than bacterial prostatitis. Transrectal ultrasound permits a perfect evaluation of prostate, seminal vesicles and ejaculatory ducts. Fifty-five patients affected by prostatis syndrome and with negative bacteriological studies, underwent transrectal ultrasonography performed with 7.5 MHz probe. In 38 cases (70%) we found abnormalities such as subacute vesiculitis, asymmetric dilation of the seminal vesicle, dilated and calcific ejaculatory ducts, mullerian duct cyst, utricular cyst and calcification. Ultrasonography is able to detect these lesions that often are responsible of the clinical symptom of the prostatitis syndrome, and may have a therapeutic value through guided transperineal needle aspiration or in the planning specific endoscopic surgery.