In order to evaluate effectiveness and tolerance of treatment with 300 mg tablets of enoxacine (one every 12 hours), 30 patients between the ages of 29 and 75 were selected (51.23 +/- 2.19 yrs. was the average age), 4 males and 26 females; 18 patients had acute cystitis, 7 had pyelonephritis, 4 had cystopyelitis, and 1 had urethroprostatitis. Treatment lasted on average of 10.77 +/- 0.52 days, with a minimum of 7 and a maximum of 20 days. Initial culture analysis of urine samples ascertained the presence of microbial pathogens sensitive to enoxacine. After one week of treatment, culture analysis of urine samples did not reveal the presence of these pathogens, all having been successfully eliminated. The improvement of the objective and symptomatic parameters chosen for evaluating the effectiveness of the treatment was found to be rapid and decisive in the majority of patients. The systemic tolerance was good; the side effects were minimal (three cases of slight gastroenteric intolerance). At the end of treatment, results were considered excellent in 18 patients and good in 12, on the basis of the more or less rapid resolution of the clinical and symptomatic situation.