In an open, nonblind study, 10 patients with Tourette's disorder who were being treated with haloperidol were videotaped before, while, and after chewing nicotine gum. The frequency of tics was reduced significantly during the 30-minute gum-chewing period and during the 1 hour after gum chewing. Nicotine appears to potentiate haloperidol effects in patients with Tourette's disorder.