OBJECTIVE: To study whether diabetic women with asymptomatic bacteriuria have impaired granulocyte function and compare them with nonbacteriuric diabetic women. RESEARCH DESIGN AND METHODS: A prevalence study with granulocyte function testing in a randomly selected number of patients was conducted; the setting was the university. The patients consisted of 63 women visiting the outpatient clinic for routine control of their diabetes. Measurements of routine blood controls and urine cultures were conducted in all patients. Granulocyte function testing (chemotaxis, opsonization, oxidative burst, phagocytosis, and killing) was performed in the first 20 patients (10 with and 10 without asymptomatic bacteriuria) and in 7 healthy control subjects. RESULTS: The prevalence of bacteriuria was 32%. Demographic characteristics were not significantly different between bacteriuric and nonbacteriuric women. Leukocytes were found more often in the urine of bacteriuric women (P < 0.05). No differences in any of the granulocyte function tests were documented among diabetic women with true asymptomatic bacteriuria, nonbacteriuric women, and healthy control subjects. CONCLUSIONS: The prevalence of asymptomatic bacteriuria is increased in women with diabetes. Granulocyte function impairment, however, cannot be the explanation for this finding.