Bacteriuria has been studied in 407 patients treated with clean intermittent catheterization (CIC) during 1 year. Significant bacteriuria was found in 50.6% of 1413 analyzed urine samples. Escherichia coli was the dominating species (54.8%). The relative distribution of species was different in males and females, but there were no differences between the CIC patients and a reference group of outpatients. On the other hand, a higher frequency of resistance among enterobacteria was found in samples from CIC patients compared to the reference group. The majority of CIC patients with bacteriuria had no symptoms, and bacteriuria per se does not seem to be an indication for treatment in most of these patients.