The present study focused on the preliminary phytochemical screening and anti-hyperglycemic effect of the roots of Arbutus unedoL. belonging to family Ericaceae. Preliminary qualitative chemical tests for aqueous, acetone and etheric extracts of the roots revealed the presence of various classes of compounds such as tannins, flavonoids, saponins, amino acids and alkaloids. The effect of aqueous extract was evaluated by using in vivo methods on normal and streptozotocin (STZ) induced-diabetic rats (STZ: 50 mg/kg, iv). Animals were treated orally by the aqueous extractat a dose of 100 mg/kg body weight for four weeks. Glycaemia and body weight were measured at specific intervals.Our results indicated that the aqueous extract produced a significant fall (more than 51%.) in blood glucose in diabetic rats Nevertheless, on normal rats the aqueous extract has no effect and glycaemia is being normal without significant variation. These findings demonstrate that the aqueous extract of Arbutus unedoL. roots have a good anti-hyperglycemic activity in streptozotocin-induced diabetic rats and this effect might be at least due to the presence of active components. Significant results obtained in the estimated parameters confirmed the use of the plant in the traditional medicine.