A total of 87 children were treated for lower urinary tract infection. The infection site was determined on the basis of symptoms and laboratory findings. The patients were assigned to four groups, medicated for 3 and for 14 days with nitrofurantoin or cotrimazole. Results from the short and long-term therapies have not shown any significant differences: 9 out of 43 patients in the 3-day therapy group and 8 out of 44 in the 14-day group presented recurrences within one month.