In order to investigate the incidence, etiologic agents and number of episodes of nosocomial urinary tract infections, a prospective study was carried on at the General Hospital in Durango, Mexico. All the patients admitted to the hospital during the period of March to June, 1991, and whose hospital stay was longer than 48 hours, were included. The infection rate in 962 patients was 12.9 episodes per hundred. The service of Internal Medicine had the highest rate and Pediatrics the lowest. The infection rate was higher among older patients and there was no significant difference between genders. 73% of the patients had only one episode of infection and the presence of a permanent urinary-catheter was the main clinical condition associated with infection. Escherichia coli and Klebsiella sp. were the most frequently isolated microorganisms. Nosocomial urinary tract infections have a very high incidence in a general hospital, therefore there is a pressing need to implement effective control programs.