Polymorphonuclear leukocytes (PMNs) in the gram-stained urethral smears of 236 consecutive sexually active men without gonorrhea were analyzed quantitatively. The frequency distribution of the highest count of PMNs per high-power field (hpf) showed a count of four PMNs to be the "cut-off" point separating men with urethritis from those without urethritis. This cut-off point correlated well with the presence of Chlamydia trachomatis as well as with turbid urine. However, the PMN count in the gram-stained urethral smear was found to be more sensitive than the appearance of the urine in the diagnosis of urethritis among those with minimal symptoms and signs and not harboring C. trachomatis. This study also demonstrated a close similarity as regards clinical features and PMN count in gram-stained urethral smears between those harboring Ureaplasma urealyticum and those with no organisms.