One hundred and ninety diabetic patients and an equal number of non-diabetic patients, age- and sex-matched, were screened for occurrence of asymptomatic bacteriuria. Of the diabetics 6.3% were found to have covert bacteriuria as were 5.3% of the control group. Asymptomatic bacteriuria was found to occur more commonly in females than males and in the patients who were over 40 years old. The incidence of bacteriuria was not found to be related to the degree of control in the diabetic patients. The most common organism cultured was E. coli.