An experiment was conducted to study the effects of Nigella Sativa (NS) and Allium Sativa (garlic) on some physiological parameters in normal and diabetic rats. The study included two experiments. The first experiment was in summer season, while the second experiment were in winter season. Each experiment included 120/each season adult male Albino rats with an average live body weight of 100±10 gm. Rats were distributed into 8 groups (15 rats each). Normal rats were fed the control diet (G1), control diet with  5% garlic (G2), 5% NS (G3) or 2.5% Garlic  + 2.5% NS (G4). However, diabetic rats were fed the control diet with 5% garlic (G6), 5% NS (G7) or 2.5 % Garlic 2.5% + 2.5% NS. Blood sample were collected after 4 and 8 weeks from the start of the experiment for determination of biochemicals and enzyme activity in blood serum. Results show that serum activity of ALT and AST, and concentration of creatinin and glucose were significantly (P<0.05) increased in diabetic rats than normal rats, but were significantly decreased after treatment with medicinal plants. Concentration of serum T3 and T4 were significantly decreased in diabetic rats than in normal rats, but were significantly increased with medicinal plants.Conclusion: The use of medicinal plants (garlic and nigella seeds) worked to improve the health of animals, and the use of garlic mixture and nigella seeds was the best effect in improving the health status of animals, especially those with diabetes.