Neuronal mechanisms involved in the jumping produced by high doses of clonidine were studied in adult mice. Intraperitoneal administrations of clonidine at doses ranging from 10 to 40 mg/kg elicited jumping behavior in dose-dependent manner, the highest frequency of jumping being observed at a dose of 30 mg/kg. The jumping behavior induced by clonidine (30 mg/kg) was decreased by pretreatment with physostigmine (0.2 mg/kg IP), apomorphine (2 mg/kg IP) and phentolamine (10 mg/kg IP), and conversely increased by atropine (5 mg/kg IP), apomorphine (0.25 mg/kg), haloperidol (2 mg/kg IP) and propranolol (10 mg/kg IP). The jumping behavior was unaffected by methylatropine (5 mg/kg IP) and mecamylamine (0.1 mg/kg IP). In addition, N6-cyclohexyl adenosine (0.2 mg/kg IP) or diazepam (2 mg/kg IP) did not affect, either. The result suggests that high doses of clonidine elicit jumping in which alpha-adrenoceptor activation, dopaminergic and cholinergic inhibition are concomitantly involved.