The study was carried out in an attempt to understand the contribution of dopamine D-1 and D-2 receptor activities to yawing responses induced by bromocriptine (BRC) in rats. Intraperitoneal (I.p.)injection of BRC ranging from 1 to 20 mg/kg produced yawing behavior. The yawing behavior. The yawing response were increased by reserpine (2mg/kg) and α-methyl-p-tyrosine (α-MPT