Roylea cinerea (D.Don) Baill. (Fam. Lamiaceae), commonly known as Ashy Royleais, and locally, kattu is widespread in the Himalaya from Kashmir to Nepal, and known for its antidiabetic activity. In this study, we evaluated the crude ethanolic extract and its sub-extracts obtained from the aerial part of R. Cinerea for antioxidant and antidiabetic activities. The antioxidant activity was evaluated by different chemical-based assays, viz. 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant potential (FRAP) and oxygen radical absorbance capacity (ORAC). The total phenolic content in R. cinerea extracts varied widely 3.87-95.3 mg GAEs/g of dry plant extract. Reduction in the blood glucose level was observed in albino male wistar rats after treatment for 15 days and the treatment with ethyl acetate extract showed highest reduction (41.13%) in blood glucose level. Serum lipid profile, hepatic glycogen content, SOD, GPx, GSH and TBARS of pancreatic tissue were also examined. The plant extract treatment increased the levels of SOD, GSH and GPx in the tissues and reduced the level of TBARS as compared to the control group. Histopathological studies showed that the treatment with plant extracts normalized the histology of pancreas and liver. These findings suggest that Roylea cinerea extracts has potent antidiabetic and antioxidant properties and thereby substantiate its use in traditional medicines. © 2017, National Institute of Science Communication. All rights reserved.