A group of 215 patients with non-insulin-dependent diabetes mellitus (NIDDM) (147 women and 68 men) were selected by home interview, and accepted to undergo clinical examination including urine culture, in order to determine the frequency of bacteriuria and its possible associations with clinical and laboratory findings. Bacteriuria was found in 17.7% of women and 1.5% of men. Univariate and multivariate analysis performed for the group of women revealed sexual intercourse and pyuria as the only factors associated with the frequency of bacteriuria. It was concluded that asymptomatic bacteriuria may be associated with sexual activity in women with NIDDM.