Midstream specimens of urine from inpatients and out.patients at King Fahd Specialist Hospital in Buraidah, Saudi Arabia, were collected over a period of 12 months to determine prospectively the frequencies of different causative organisms and their antimicrobial susceptibility. A total of 854from 4157 specimens (20.54%) gave significant bacterial counts i.e., counts greater than 10′ organisms per millilitre. Escherichia coli was the commonest organism (50.11%) followed by Klebsiella spp. (28.33%) Pseudomonas spp. (7.84%) and Proteus spp. (4.91%). Other bacterial pathogens wer…