Abstract: Palmatine given subcutaneously at the dosage of 50 mg/kg to male rats weighing 100-150 grams produced hyperaemia and oedema of the paws within half an hour. Local injection of 25 micrograms of palmatine in 0.1 ml to the hind paw elicited a similar response. Pretreatment of the rat with intraperitoneal injection of diphenhydramine (75 mg/ kg) or chlorpromazine (5 mg/kg) significantly inhibited the oedema of the hind paws induced by subcutaneous injection of palmatine. Diphenhydramine (75 mg/kg) and Dibenamine (15 mg/kg) given concomitantly, or chlorpromazine (5 mg/kg) given alone, prevented significantly the formation of oedema of the hind paws elicited by locally in- jected palmatine. Following subcutaneous injection of palmatine, the histamine content of the peritoneal fluid was found to be higher than that of the control. Therefore, the anaphylactoid reaction of the rat to the injection of palmatine is the result of histamine and probably 5-hydroxytryptamine release.