Transrectal ultrasonography was performed in 46 patients with hemospermia. Abnormal findings in the prostate and seminal vesicles, including prostatic stones, benign prostatic hyperplasia, prostatitis, and dilatation and calculi of the seminal vesicles, were observed in 34 patients (73.9%). However, no malignant lesions were found in the prostate or seminal vesicles. Transrectal ultrasonography was a useful and noninvasive procedure to investigate the causes of hemospermia. Furthermore, transrectal ultrasonography could demonstrate latent diseases and exclude malignancy of the prostate and seminal vesicle in patients with hemospermia.