The administration of the nicotinic cholinergic agonists dimethylphenylpiperazinium iodide (DMPP) or nicotine caused a concentration dependent release of [3H] dopamine, [3H]5-hydroxytryptamine as well as endogenous dopamine and 5-hydroxytryptamine from superfused slices of rat striatum. 2. Release of both labelled and non-labelled transmitter was antagonized by the nicotinic antagonist, hexamethonium but not the muscarinic antagonist, atropine. 3. The present study provides additional evidence that nicotinic-cholinergic receptors are present in the mammalian central nervous system. 4. Activation of these nicotinic-cholinergic receptors in the striatum results in the release of both dopamine and 5-hydroxytryptamine.