The aim of this study is the evaluation of the effect of Afghan talkhak (Acroptilon Repens) root aqueous extract on blood glucose level of diabetic rats. Rats were randomly divided into 5 groups (1 Normal, 1 Diabetic and 3 extract groups). Experimental diabetes was induced by single-dose intraperitoneal (i.p.) injection of streptozotocin (55 mg/kg) in diabetic and extracts groups. 72 hour later, the induction of diabetes was approved and extract groups were received Acroptilon Repens aqueous extract (200, 300, 400 mg/kg) by i.p. administration for 15 days. The blood glucose level and body weight of all groups were measured on baseline, 0, 5, 10 and 15th days. The glucose tolerance test had performed on days 0 and 15. The results showed that aqueous extract of Afghan Acroptilon Repens in extract groups (200 and 300 mg/kg) could significantly decrease the blood glucose level, and improve the glucose tolerance, as compared with the diabetic group (P<0.0001). However, there was not a significant difference in the blood glucose level and glucose tolerance test among the group which received 400 mg/kg dose of Acroptilon Repens and the diabetic group (P>0.05). In conclusion, Acroptilon Repens root aqueous extract possessed antihyperglycemic activity.