Our objective was to treat the overactive bladder caused by Detrusor hyperreflexia (in suprasacral cord neuropathic bladder) and Detrusor instability (idiopathic) by Capsaicin that was extracted from Capsicum Frutes Cens. Eleven with patientsneuropathic bladder and three patients with idiopathic Detrusor instability were enrolled. They were treated by intravesical Capsiacin at a concentration of 1 mM/L in 30% ethanol to half of the bladder capacity for 30 minutes after 2% Xylocaine without adrenaline up to half of the bladder capacity for 15 minutes. The results showed significant improvement ie. Average frequency reduced from 16.5 + 4.8 time/day to 8.6 + 2.5 time/ day Average leakage reduced from 9.7 + 8.1 time/day to 2.4 + 4.3 time/day Urodynamic results Pressure at maximal bladder capacity reduced from 71.1 + 29.2 cmH2O to 57.3 + 27.2 cmH2O Voiding pressure reduced from 74.8 + 35.3 cmH2O to 65.1 + 35.0 cmH2O