A case of T. vaginalis infection involving the median raphe of the penis is presented. The infection was contracted after sexual exposure. The patient had no urethral discharge but had a penile swelling that discharged pus. Microscopic examination and culture of the discharge showed the presence of T. vaginalis. Treatment with metronidazole (250 mg thrice daily for 7 days) eradicated the infection, but the swelling remained and a cyst was excised. One month after the surgical procedure, the patient was clinically normal and cured of the infection.