Hemospemia, the presence of blood in the semen, is an uncommon symptom. It does, however, frequently cause the patient's concern, particularly due to fear of cancer. Transrectal ultrasonography was performed in 18 patients with hemospermia from June 1994 to June 1996. Four patients showed normal findings and in 14 patients' (78%) findings were abnormal. These included seminal vesicle dilatation (5 patients), seminal vesicle cyst with calculi (2 patients), prostatic calculi (2 patients), seminal vesicle dilatation with prostatic cyst (4 patients) and seminal vesicle dilatation with prostate calculi (1 patient). However, no malignant lesions were found in the prostate or seminal vesicles. Transrectal ultrasonography is a useful and noninvasive procedure to investigate the cause of hemospermia. Furthemore, transrectal ultrasonography could demonstrate latent diseases and exclude malignancy of the prostate and seminal vesicles in patients with hemospermia.