Microscopy and leukocyte esterase activity, both employed as screening techniques for urine cultures, were evaluated with respect to two distinct populations, male and female. When 424 urine specimens from males were examined, 95% of the Gram-stained smears and 91% of the leukocyte esterase tests correctly correlated with culture results, indicating significant bacteriuria. There were no significant differences between the Gram stain and leukocyte esterase activity in predicting a negative culture: 99% and 98%, respectively. Neither microscopy nor esterase activity proved as sensitive or as efficient in predicting a negative culture with the female population.