['Short courses of antibiotics are often recommended to treat children with acute cystitis despite lack of firm evidence to support such management. The aim of this study therefore was to analyse the short-term outcome of such treatment. The retrospective analysis included 300 children (252F, 48M) fulfilling the criteria of first-time acute cystitis and managed according to a protocol recommending 5 d treatment. In 214 (71%) the treatment was given according to the protocol and in the others for 7 or 10 d. Nitrofurantoin was used in 150 (50%) and trimethoprim without or with sulfonamide in 129 (43%). The short-term results were excellent with 96% of the children being free from symptoms at the first follow-up visit after a median of 6 d. Only 2 girls had persisting bacteriuria and thus the frequency of bacteriological treatment failure was 1%. Recurrence within 30 d occurred in 4 girls (2%).'] Is antibiotic treatment for five days effective in children with acute cystitis?