Objective: To find the efficacy and optimal dosage of oxybutynin HCl in a group of enuretic children, who were non-responsive to imipramine. Material and Methods: Thirty-six patients with enuresis who were non-responsive to imipramine were urodynamically assessed and subsequently treated with oxybutynin hydrochloride (HCl). Patients with inadequate bladder storage function (IBSF) were started on 10-mg daily oxybutynin HCl for one month. If the initial treatment was found to be inadequate, the dose was increased to 15 mg daily. The dose in patients who were non-responsive to 15-mg daily dose was increased to 20-mg daily dose. Patients who were normal urodynamically were treated with a dose of 15 mg daily for one month. Results: Before the treatment, 17 patients had IBSF (47.2%). The majority of the patients (88.2%) with IBSF were responsive to the 15-mg daily oxybutynin HCl. The treatment in patients with normal bladder function was generally unsuccessful. Conclusions: Oxybutynin HCl in sufficient dosages seems to be effective in the treatment of enuretic patients with IBSF.