The effects of a reversible activator of adenylate cyclase sclareol glycol (SG), a semisynthetic diterpene of the labdane family, on the aggressive behavior induced by a high dose of clonidine in mice were studied. SG was applied at doses well below the lethal dose. Aggressive behavior induced by clonidine at a dose of 30 mg/kg IP was decreased in a dose-dependent manner by SG (1, 5, 25 mg/kg IP). The aggressive responses were abolished by doses of 50 and 100 mg/kg. It is suggested that the inhibitory effects of SG on clonidine-induced aggressive behavior are realized mainly via its effect on adenylate cyclase and perhaps involving synaptic transmitter action.