15 patients with neurogenic detrusor hyperactivity refractory to oral anticholinergics received a daily intravesical instillation of 5 mg of oxybutinin for 6 days. An improvement was observed clinically in 10 cases and on urodynamic parameters (60% increase in bladder capacity, doubling of the volume inducing an urge to void) in 12 cases. The mechanism of action is discussed.