Aim: The aim of this study was to investigate the effect of PTNS after 12 weeks, on the urodynamic findings in the Multiple Sclerosis (MS) patients with neurogenic detrusor overactivity (NDO). Methods: A total of 19 MS patients with NDO were enrolled in the study. Urodynamic studies before and after 12 weeks PTNS were performed. PTNS was applied unilaterally from the medial malleolus and posterior to the edge of the tibia by using chargecompensated 200 mu s pulses with a pulse rate of 20 Hz, weekly, during 3 months. The effects of PTNS on urodynamic variables were compared of baseline and after PTNS data in MS patients. Results: Mean volume at the first involuntary detrusor contraction (1st IDCV) on standard cystometry was 124.2 +/- 37.6 ml, while it was 217.5 +/- 66.4 mL after PTNS. Mean maximum cystometric capacity (MCC) on standard cystometry was 199.7 +/- 29.3 mL, while it was 266.8 +/- 36.9 mL after stimulation. The improvements in the 1st IDCV and MCC were statistically significant after stimulation. Mean P(detmax) at first involuntary detrusor contraction, maximal detrusor pressure at maximum cystometric capacity, detrusor pressure at maximal flow (P(detQmax)) and maximal flow rate (Q(max)) were statistically significant after PTNS for 12 weeks. Conclusions: These results have demonstrated that PTNS is effective to suppress NDO in MS patients after PTNS. Although long-term efficacy of PTNS is known, the findings showed prominent improvements on the clinical and urodynamic outcome, we think that the use of PTNS for DO in MS patients will be promising in clinical practice in the future. Neurourol. Urodynam. 28:964-968, 2009. (C) 2009 Wiley-Liss, Inc.