The penetration of ofloxacin into prostatic fluid, ejaculate and seminal fluid was measured by a high-pressure liquid chromatography (HPLC) method after intravenous infusion (60 min) of 400 mg in six healthy male volunteers. The median concentration of ofloxacin in prostatic fluid was about one-third and that in ejaculate and seminal fluid about twice that in corresponding plasma. The results of the study indicate good penetration of ofloxacin into prostatic fluid, ejaculate and seminal fluid. Ofloxacin should thus be of value for the treatment of chronic bacterial prostatitis and vesiculitis.