Clonidine, an α2 adrenoreceptor agonist, induces dose dependent catalepsy in mice, which releases histamine from mast cells which is responsible for different asthmatic conditions. Ricinus communis Linn (Euphorbiaceae) is a medicinal plant; root is sweetish and has been used traditionally in the treatment of inflammation, pain fever, asthma, bronchititis and leprosy. In present study ethanol extract of R. communis roots (ERCR) at doses 100, 125 and 150 mg/kg intraperitoneally was evaluated for antihistaminic activity using clonidine induced catalepsy in mice. Finding of investigation showed that chlorpheniramine maleate and ERCR inhibit clonidine induced catalepsy significantly P < 0.001 when compare to control group. Present study concludes that ERCR possesses antihistaminic activity.