The purpose of this study was to assess urodynamics parameter changes induced by acute sacral neurostimulation (SNS) in spinal cord injury (SCI) patients with neurogenic detrusor hyperreflexia. Fourteen SCI patients with urge incontinence owing to a hyperreflexive bladder were prospectively evaluated. Neurostimulation was performed on the root that obtained the best motor response (10 Hz, 210 microseconds) and amplitude ranges of >0 to 10 V. The urodynamics study was done in the prone position. Four cystometries were recorded before (two), during (one), and 10 minutes after stimulation (one). Maximal bladder capacity (MBC) (volume to first leakage), bladder volume at first uninhibited contraction (BV(1stC)), and maximal detrusor pressure during uninhibited contractions (P(det)max) were compared. Left S3 foramen was the most commonly used (9/14). Mean amplitude of stimulation was 4.5 V (range, 0.5-8.5 V). Statistically significant differences (Mann-Whitney U-test) were found for MBC, BV(1stC), and P(det)max with mean variations of +206.8 mL (+107%, P < 0.001), +151.5 mL (+98%, P < 0.01), and -23.4 cm H2O (-27%, P < 0.05), respectively. Patient gender and SCI level did not reveal any difference. Patients who reached a MBC of up to 400 mL (+278.2 mL, +129%, n = 10) with SNS had statistically significant improvement of BV(1stC) (+210.2 mL, +125%, P < 0.01) and P(det)max (-33.3 cm H2O, -38%, P < 0.01). Acute temporary SNS in SCI patients has a profound effect on key urodynamics parameters. These neurologically impaired patients with detrusor hyperreflexia may be appropriate candidates for implantable SNS.