OBJECTIVE We investigated the effects of tibial nerve stimulation on bladder overactivity induced by acetic acid irritation. METHODS Cystometry was performed in 10 α-chloralose anesthetized female cats by infusing saline or acetic acid through a urethral catheter that was secured by a ligature around the urethra. Intravesical infusion of 0.25% acetic acid was used to irritate the bladder and induce bladder overactivity. Multiple cystometrograms were done before, during and after tibial nerve stimulation to determine the inhibitory effect on the micturition reflex. RESULTS Infusion of 0.25% acetic acid irritated the bladder, induced bladder overactivity and significantly decreased bladder capacity to about 20% of control capacity measured during saline infusion. Tibial nerve stimulation at low (5 Hz) or high (30 Hz) frequency significantly increased bladder capacity to about 40% of saline control capacity when it was applied during acetic acid infusion cystometrogram. Bladder contraction amplitude was smaller during acetic acid irritation than during saline distention due to significantly smaller bladder capacity. Tibial nerve stimulation at 5 Hz increased bladder capacity and bladder contraction amplitude. CONCLUSIONS Activation of somatic afferents in the tibial nerve of cats can partially reverse the bladder overactivity induced by intravesical administration of a chemical irritant that activates C-fiber afferent nerves. These data are consistent with clinical studies showing that tibial nerve neuromodulation is effective treatment for overactive bladder symptoms.