Urinary tract infection remains a common clinical problem. In comparison with the intense research on diagnosis and management, relatively little attention has been focused on the behavioral and genetic factors that may relate to an increased risk of urinary tract infection. Among behavioral risk factors in women, sexual activity and diaphragm spermicide use are clearly associated with increased risk; postcoital voiding and voiding soon after the urge to urinate may be protective factors. Data regarding other behavioral risk factors in women have been inconclusive. In men, identified behavioral risk factors have included rectal intercourse and lack of circumcision. Regarding genetic influences, it appears that a woman's blood group secretor status influences her susceptibility to recurrent urinary tract infection.