In order to compare the incidence of symptomatic urinary tract infection (UTI) in diabetic patients with and without asymptomatic bacteriuria (ASB), and to identify other risk factors for these infections, 289 females and 168 males were studied over a 12-month period. Symptomatic UTI occurred in 69.2% of patients with ASB (67.6% female and 76.5% male) versus 9.8% without ASB (14.9% female and 2.6% male). ASB and urinary incontinence were associated with symptomatic UTI in both women and men. Other risk factors included previous antimicrobial treatment and macrovascular complications in women and obesity and prostatic syndrome in men. The presence of ASB was found to be the major risk factor for developing symptomatic urinary tract infection. Further prospective randomized clinical trials of diabetic patients with risk factors for UTI who are receiving or not receiving treatment may be considered.