Effects of YM-09151-2 and five other neuroleptics (haloperidol, spiperone, chlorpromazine, sulpiride and clozapine) on the binding of [3H]-ligands to nine different receptors (alpha 1-adrenergic, alpha 2-adrenergic, beta-adrenergic, muscarinic, D2-dopaminergic, H1-histaminergic, 5HT1-serotonergic, 5HT2-serotonergic and opiate receptors) and on dopamine-sensitive adenylate cyclase were determined using brain membranes in the rat, guinea-pig and dog. The affinity of YM-09151-2 for D2-receptors with a Ki value of 0.1 nM was more than 1000-times higher than that for the other receptors and dopamine-sensitive adenylate cyclase, and it was the greatest among the neuroleptics tested.