In order to examine the relative frequency of urinary tract infection (UTI) and bacteriuria among male nursing home patients managed with and without external catheters (EC), we prospectively followed four cohorts of patients (EC worn continuously, N = 30; EC worn at night only, N = 19; incontinent without catheter, N = 13; and continent, N = 30) for a total of 497 patient months at risk. The proportion of patients with EC worn continuously who had at least one episode of bacteriuria (87%) and at least one UTI (40%), and the incidence of UTI (0.08 episodes per patient-month at risk) was significantly higher than among continent or incontinent patients without EC. Patients with EC at night only had an intermediate frequency of these findings. Differences in clinical and functional status characteristics among the four cohorts, in addition to the use of EC, could have contributed to the higher frequencies of bacteriuria and UTI. None of the clinical characteristics we examined were associated with the development of UTI among patients with EC. Further studies are necessary to identify factors associated with UTI among patients who are managed by EC so that effective preventive strategies can be developed and targeted to patients at high risk.