Abstract: Camellia sinensis or tea belonging to the family of Theaceae, is widely grown. In Mazandaran provinces in the north of Iran. Tea is known in folk medicine as a medicinal plant that used as hypotensive and anti-diabetic. In this research the aqueous green leaf extract of Camellia sinensis (450 mg kg-1) showed a strong glucose lowering effect after oral administration in rats. The decrease of glycemia has reached to 30% of the control value 2 h after glucose loading. The amount of glucose absorbed in a segment jejunum in situ was 9.2±0.2 mg in presence of tea extract vs. 14.11±0.91 mg in control rats during 2 h (p<0.05). The results indicate that aqueous extract of tea has a significant anti hyperglycemic effect that may be caused in part by the reduction of intestinal glucose absorption.