Objective: We aimed to investigate median lethal dose(LD50) and hypoglycemic effect of fixed oil ofFoeniculum vulgare Miller seed fixed oil (FFO) in miceand its hepatoprotective effect on carbon tetrachloride(CCl4) induced liver injury model in rats.Method: Extract of FFO, glibenclamide (as a referencegroup) and physiologic saline (control group) wereadministrated to the healthy and diabet occured micewith alloxan. Before treatment in the first, second, third,fourth and 24th hours, blood was taken from the venacoccygea of mice. Blood glucose levels weremeasured.Twenty-four Sprague-Dawley rats were divided intofour groups (n=6), and the groups treated daily forseven days, by i.p. injections, of isotonic saline solution(ISS), olive oil, carbon tetrachloride (CCl4), CCl4 + FFOrespectively.Results:  FFO did not significantly reduced bloodglucose in alloxane-induced diabetic mice comparedto ISS control group. In contrast, glibenclamideeffectively reduced blood glucose of alloxane-inducedmice in first, second, fourth and 24th hours as expected.In the CCl4-treated group and FFO-treated group serumaspartate aminotransferase (AST), alanineaminotransferase (ALT) and alkaline phosphatase(ALP) levels were quite high. In contrast, the controlgroups (group I and group II) had significantly lowerlevels of AST and ALT when compared with the CCl4and FFO groups.Conclusion: The results of this study indicate that FFOhas neither a potent hepatoprotective effect againstCCl4-induced hepatic damage in rats nor ahypoglycemic action in mice. The LD50 of FFO wasdetermined as 5.52 mL/kg.Key words: Foeniculum vulgare Miller, fennel fixed oil,median lethal dose, hepatoprotective effect, hypoglycemiceffect.