Dillenia indica Linn. (Family: Dilleniaceae) is an evergreen tree, 30–80 ft. in height, which bears large and hard fruit of 3–5 in. in diameter and grows in moist and evergreen forests of India. The ripe fruits are widely used in flavoring of curries and preparation of jam and jelly. The acid juice is sweetened with sugar and used as a cooling drink [1]. The mixed juices of leaves bark and fruits are given orally for the treatment of cancer and diarrhea [2]. Traditionally, the plant is also used for treatment of diabetes [3]. The literature survey revealed that there is no experimental evidence of antidiabetic effect of the plant. Therefore, the present work was undertaken to explore hypoglycemic and hypolipidemic properties of Dillenia indica methanolic leaves extracts in streptozotocin induced diabetic wistar rat by administering graded oral doses (250 and 500mg/kg body weight) for 21 days. The extract showed significant antidiabetic activity (p<0.01). Furthermore, the decreased body weight of rats was significantly improved after extract treatments. Daily oral treatment with the extract for 21 days to diabetic rats, also resulted in significantly reduction in serum cholesterol, triglycerides and serum transaminase levels but HDL-cholesterol level was found to be improved (p<0.01) as compared to diabetic control group. The extract treatment also showed to enhanced serum insulin level in diabetic rats as compared to diabetic control group.