Objectives Trichomonas vaginalis is one of the pathogens causing sexually transmitted infections. This microorganism is a common pathogen among women, but its significance as a cause of morbidity among men remains uncertain. We sought to determine the prevalence and morbidity of T. vaginalis infection in Japanese men with and without urethritis.

Methods We examined urine specimens from 215 men with urethritis and 98 men without urethritis for the presence of urethral T. vaginalis by PCR assay.

Results Only four patients—one with gonococcal urethritis, one with non-gonococcal chlamydial urethritis, one with non-gonococcal non-chlamydial urethritis and one without urethritis—were positive for T. vaginalis. The prevalence of T. vaginalis was 1.4% in men with urethritis and 1.0% in men without urethritis. A possible relation between the appearance of T. vaginalis and clinical symptoms was not confirmed.

Conclusions In the present study, the incidence of urethral T. vaginalis infection appears to be rare in Japanese men with or without urethritis, and T. vaginalis may be an uncommon pathogen in male urethritis in Japan.