Here we report the unusual case of a patient who suffered neurological deficit of the facial nerve as a complication of a root canal treatment. During the canal treatment, 3% hydrogen peroxide and 90% ethanol rinses were performed. The present case demonstrated rinse toxicity to vital tissue as evidenced by severe clinical damage. Chlorhexidine can be used instead of potentially toxic rinses with good antimicrobiological results. Furthermore, special attention should be paid to determination of the root canal length and the integrity of the canal system before rinsing. Also irrigation should be applied at a low pressure.