To assess the efficacy of desmopressin plus oxybutynin and compare two starting dosages of desmopressin (120 and 240 µg) in a randomized, double-blinded, placebo-controlled trial for children with monosymptomatic nocturnal enuresis (MNE) resistant to desmopressin. The predictive factors of children with MNE responsive to desmopressin and combination therapy were also evaluated.