The powdered seeds of Acacia arabica and roots of Caralluma edulis were administered in doses of 2, 3 and 4 gm/kg body-weight to normal and alloxan-diabetic rabbits. The blood glucose levels were estimated before and 2, 4, 6 and 8 hours after the administration of plant suspension. The powdered seeds of Acacia arabica exerted a significant (P less than 0.05) hypoglycemic effect in normal rabbits. The hypoglycemic effect was not significant (P greater than 0.01) in alloxan diabetic rabbits. The powdered roots of Caralluma edulis did not produce any significant (P greater than 0.01) hypoglycaemic effect in normal as well as in alloxan diabetic rabbits. The doses used did not show any acute toxicity and behavioural changes. From this study it may be concluded that the powdered seeds of Acacia arabica act by initiating the release of insulin from pancreatic beta cells of normal rabbits. Moreover, Caralluma edulis did not show any hypoglycaemic effect in normal as well as in diabetic rabbits.