A 48-year-old heterosexual Japanese man visited the outpatient clinic of Nagoya Urology Hospital, complaining of burning pain at voiding and pus discharge from the urethral orifice. These symptoms appeared the day following oral-genital contact (fellatio) with a commercial sex worker. On the basis of the presumptive clinical diagnosis of gonorrhea because of the microscopic detection of diplococci in the urethral discharge, he was treated with levofloxacin (300 mg per day) for 7 days. His symptoms responded quickly and urinalysis taken 7 days later was normal. Microbiological examinations isolated Neisseria meningitidis in the urethral discharge by culture with the use of enzymatic profiles. Further prevalence of sexually transmitted diseases (STD) through oral-genital contact would lead to an increase in meningococcal urethritis.