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Background: diabetes is a chronic disease that despite of medical and specific treatments has reminded as an important medical problem. Various herbal were presented for treatment of diabetes. One of these plants is Prosopis farcta that was used as hypoglycemic agent in traditional medicine. The aim of this study was investigation of hypoglycemic effect of Prosopis farcta root in diabetes and healthy rats. Methods: root of plant was collected from southern area of Iran. Plant was extracted through percolation. Healthy rats were divided to control group and receiver extract (12 g/kg). streptozotocin diabetic rats were divided to six groups. 3 groups were treated by plant extraction (4, 8 and 12 g/dl), one group by Glibenclamide (10 mg/kg), one group by NPH insulin (5IU/kg) and one group by normal saline (1 ml/kg). Blood sample were taken at 0, 1, 2, 3, 5, 7, 24 and eighth day after treatment from rat tails. Blood glucose levels were measured by glucometer. Findings: preliminary photochemical analysis showed root extract consist of tannin, flavonoid, saponin and alkaloid. Root extract with various doses (4, 8 and 12 g/dl) had not any efficacy on decrease of blood glucose among diabetic and healthy rats. Glibenclamide and insulin decrease significantly blood glucose in diabetic rats. Conclusion: No appear that root extract of this plant to be useful on lowering blood glucose. More research are needed to identify another efficacy and chemical component of this plant