We treated 166 patients suffering from recurrent urinary tract infections under double-blind conditions for 3 months with 1 capsule daily of either the immunostimulating bacterial extract (85) or a placebo (81), followed by a 3-month observation period without the test drugs. The bacterial extract exerted a significant beneficial curative action and long-term consolidative effect on the frequency of recurrent urinary tract infections with marked improvements in the characteristic signs and symptoms. It was significantly superior to placebo for the majority of the assessed parameters: number of recurrent urinary tract infections, bacteriuria, leukocyturia, erythrocyturia, nitrituria, albuminuria and casts in urine. Consumption of antibiotics, chemotherapeutics, urinary antiseptics or disinfectants was significantly less under active drug therapy compared to placebo. Tolerance was good with only 2 side effects reported in 2 patients (2%) in the active group compared to 11 among 5 (6%) in the placebo group. Therefore, the bacterial extract can be considered an efficient and well tolerated drug for the treatment of urinary tract infections, and their accompanying signs and symptoms, as well as for decreasing the risk of recurrences and the need for antibiotics and other antibacterial drugs.