Background: Diabetes mellitus and hyperlipidemia are well-known risk factors for several illnesses including atherosclerosis, heart and vascular diseases and stroke. Herbal medicine is still the mainstay of about 75–80% of the world population, mainly in the developing countries, for primary health care because of better cultural acceptability, better compatibility with the human body and lesser side effects. Herbal extracts are introduced to the mankind since many centuries, several herbal extracts in different oral formulas have been recommended for diabetes mellitus and hyperlipidemia treatment all over the world. Objective: The present study was carried out to investigate the hypoglycemic, hypolipidemic and antioxidative effects of the extract of Bitter melon (Citrullus colocynthis) in young adult Sprague Dawley female rats for eight weeks. Materials and Methods: Forty female young adult Sprague Dawley female rats were divided into two sections. Section I (Normal animals) was S.C. injection with a vehicle (0.9% NaCl) and divided into two groups (10 rats / group), one of these served as control group and the second group was received extract of Bitter melon (Citrullus colocynthis) seed 50 mg/kg/day for 8 weeks and served as normal treated group. Group II was S.C. injection with Alloxan (diabetic rats) and divided into two group (10 rats each), one of these served as diabetic control group while the second group was received extract of Citrullus colocynthis (C-colocynthis) seed (50mg/kg/day) orally for 8 weeks and served as diabetic treated group. After 8-weeks experiment was terminated and animals were sacrificed, heart blood was drawn and sera were separated for assessment of blood glucose, lipid profile, and lipid peroxidation value (MDA), reduced glutathione (GSH), lactate dehydrogenase (LDH), alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) as well as total and direct bilirubin. Results: Both normal and diabetic rats showed a significant decrease in blood glucose, lipid peroxidation value (MDA), total cholesterol (TC), triglycerides (TG) as well as total and direct bilirubin. While, levels of reduced glutathione (GSH), lactate dehydrogenase (LDH), alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and total lipid were significantly increased in both normoglycemic and hyperglycaemic rats except ALT, AST and ALP in hyperglycaemic rats had no changes. Conclusions: The present study shed more of the light on the effect of Bitter melon (Citrullus colocynthis) extract and proves that this extract has antioxidant, hypoglycemic and hypolipidemic properties in the rats and may be used for treating diabetes mellitus.