Facial synkinesis and asymmetry commonly impair the outcome of facial nerve palsy. Botulinum toxin type A is a neurotoxin which prevents acetylcholine release at the neuromuscular endplate, paralysing skeletal muscle. This paper examines its use in 24 patients with synkinesis and asymmetry affecting the eye and mouth. Sixty-eight of 72 treatments produced improved cosmesis. Dose-related complications occurred in 26 treatments but were generally mild and transient. The total dosages of toxin used were analysed. The higher dose group compared with the lower dose group had no significant advantage in overall cosmetic improvement but the complication rate was significantly higher in the higher dose group (20/39) compared with the lower dose group (6/33) (chi 2 6.675, P > 0.05).