The effect of theophylline (5, 15, or 30 mg/kg sc) on the catalepsy induced by haloperidol in the rat was studied. Theophylline was shown to induce a dose-dependent inhibition of this catalepsy. These data support the hypothesis that the methylxanthines are dopamine agonists and suggest that coffee, tea, and cola drinks should be avoided by patients undergoing neuroleptic treatment.