Fifty-two patients, all of whom were more than 66 years-old and who were hospitalized for periods in excess of two years were treated for chronic urinary tract infection. All patients received a course of antibiotic treatment for seven to ten days and were then put onto treatment with methenamine hippurate 1 g twice daily for six months. Of the original fifty-two patients, twelve did not complete the six month course. During the six month period with "Hiprex' there were far fewer re-infections than in the previous six months during which time they had received intermittent antibiotic therapy and other long-term treatment. There were no adverse reactions and bacterial resistance did not occur.