An experiment was conducted to study the effect of feeding Allium Sativum (AS) at three levels 4 ,6 and 12% on serum glucose, insulin and some physiological parameters in male rats. This study included 24 adult male albino rats, with an average live body weight 140 gm. Rats were distributed into 4 groups (6 rats each). Blood samples were collected at 8 am , 4 pm and 12 pm twice after 4 then 8 weeks from the beginning of the experiment . Blood samples were centrifuged at 3000 rpm for 15 min to obtain serum. Results show that AS did not show any significant effect on serum glucose after 4 weeks, meanwhile after 8 weeks 4% AS was significantly decreased serum glucose. Serum glucose tended to be higher at 4 pm in control and most treated groups after 4 or 8 weeks from the start of the experiment. Treatment with 4 % or 6% AS for 4 weeks significantly increased serum insulin. Serum insulin were increased at 8 am after 4 weeks ,while after 8 weeks serum insulin were increased  at 12 p.m. AS significantly decreased serum total protein and albumin after 4 or 8 weeks as compared with the control group .Serum cholesterol were increased after treatment with AS. .AS did not show any significant effect on serum triglycerides after 4 weeks, Meanwhile after 8 weeks AS significantly decreased serum triglycerides .After 4 weeks from the treatment 4% and 12 % AS significantly increased serum alkaline phosphatase , while after 8 weeks all groups treated with AS significantly decreased Alkaline phosphates .serum creatinine significantly decreased after treatment with AS for 4 weeks ,while after 8 weeks from the treatment 4% and 12 % AS significantly decreased serum creatinine as compared with the control group . It could be concluded that the addition of several levels of garlic in rats diet cause a several effect on some blood components under study. Feeding of diet contain garlic enhance serum insulin and glucose levels in the experimental rats. Thus we can add garlic to rat's diet by 4% or 6% from the diet to increase the performance in this animal.