Acute urinary tract infection (UTI) is an extremely common clinical entity that affects almost half of all women in the United States, and accounts for more than 7 million physician visits, annually, in this country. Sexual behavior and UTI history are the most important predictors of UTI risk among sexually active young women. Whether sexual behavior has similar impact on UTI risk in older women is unknown. Postcoital prophylaxis has been investigated as a strategy for the prevention of recurrent UTI in sexually active women. There are conflicting data regarding the role of voiding habits in relation to sexual intercourse and the risk of UTI. Finally, there are interesting epidemiologic studies suggesting that uropathogenic Escherichia coli may be transmitted between sex partners. We review the recent literature regarding these different areas, and comment on the potential role of sexual transmission in UTI.