Background and Objective: Use of medicinal plants for attenuation of hyperglycemia and restoration of lipids to normal level is clinically very important. In this study, the effect of oral administration of Lycium barbarum (LB) fruit on serum glucose and lipids was investigated in diabetic rats. Materials and Methods: Thirty two female Wistar rats were divided into 4 groups control, LB-treated control, diabetic, and LB-treated diabetic groups. The treatment groups received oral administration of plant (fruit)-mixed pelleted food (at a weight ratio of 6.25%) for 6 weeks. Serum glucose, triglyceride, total cholesterol, LDL- and HDL- cholesterol levels were determined before the study, and at 3rd and 6th weeks after the study. Results: LB treated diabetic rats showed a significant reduction in glucose level compared to non treated group at 3rd and 6th weeks (P<0.01- 0.005). There were no significant changes regarding to total serum cholesterol and triglyceride levels. Meanwhile, LB administration significantly increased HDL-cholesterol level (P<0.05) and reduced LDL-cholesterol level (P<0.01) in treated diabetic group as compared with untreated diabetic group. Conclusion: Oral administration of LB fruit has a significant hypoglycemic effect and led to appropriate changes only in high density lipoprotein-cholesterol and low density lipoprotein cholesterol.