Asymptomatic bacteriuria is frequent in elderly, populations. The major contributing factors are selected physiologic aging changes and comorbid illnesses, which occur with increased frequency in these populations. There is little short-term or long-term adverse outcomes attributable to this high prevalence and incidence of asymptomatic bacteriuria and no evidence for an impact on survival. A number of important questions relating to this problem have yet to be resolved. First, further studies in the noninstitutionalized population are needed to characterize the incidence of asymptomatic infection and its relationship to symptomatic infection. In the institutionalized population, studies to refine the clinical diagnosis of symptomatic urinary infection occurring in a population with such a high prevalence of asymptomatic bacteriuria are needed. In addition, further assessment of the impact of the reservoir of asymptomatic bacteriuria in elderly institutionalized subjects as a contributor to the problem of antimicrobial resistance in the institutionalized population should be a priority.