Nicotine was found to markedly potentiate haloperidol-induced hypokinesia in rats. Nicotine alone was without effect. Subsequently, concurrent administration of 2 mg nicotine gum to 10 Tourette syndrome patients being treated with haloperidol produced a substantial decrease in tics and improvement of concentration and attention span. Nicotine gum alone was without effect. While 80% of children showed improvement with nicotine gum, 70% completely discontinued the gum because of side-effects, primarily involving nausea and bitter taste. Nicotine may prove useful for treating other neuroleptic responsive disorders, such as schizophrenia and Huntington's disease.