The faecal, introital, and urinary bacterial flora have been studied in 3 normal women and 5 women with recurrent urinary infection. In the normal women urinary abnormalities were uncommon, but the patients regularly had episodes of bacteriuria and pyuria, only a quarter of which were symptomatic. Symptoms tended to be associated with high white cell excretion rates and with the longer episodes. Introital colonisation was heavier and more frequent in the patients than in the control subjects. Organisms recovered from the urine had previously colonised the introitus in most cases. It appears that symptomatic episodes constitute only a small part of the disease process in patients with recurrent urinary tract infection.