230-239Rheum nobile Hook. f. & Thomson (family Polygonaceae) is extraordinary, unexploited, and vulnerable Himalayan rhubarb with high ethnomedicinal values. Traditionally in Nepal, its rhizomes are used to relieve pain, swelling, and in bone fractures. In this study, several in vitro and in vivo assays of the rhizome extracts were carried out. The hexane, dichloromethane, ethyl acetate and butanolic extracts obtained after fractionation of 95 % ethanolic extract showed potentially cytotoxicity against Artemia salina nauplii and antibacterial effect. The 80 % ethanolic extract displayed sedative effect in mice (ED50 = 100.32 mg/kg). The same extract inhibited 66.60 and 81.49 % of acetic acid-induced writhes in mice at doses 250 and 400 mg/kg, respectively (p p Rheum