Macaranga denticulata (Blume) Müll.Arg. (family Euphorbiaceae) is an evergreen tree and a common pioneer species in moist open and secondary forest. It is commonly known as Kharpa in Mizoram. Traditionally, the species of Macaranga are used in the treatment of swelling, cuts, sores, boils and bruises. Preliminary phytochemical screening and evaluation of in vitro antioxidant activity were carried out on the methanolic extract obtained from the bark of M. denticulata. The presence of alkaloids, tannins, flavonoids, saponins, steroids and triterpenoids was indicated by the tests conducted. The in vitro antioxidant activity was evaluated using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, reducing power and hydrogen peroxide radical scavenging activity. Ascorbic acid and butylated hydroxytoluene (BHT) were used as reference standards. The methanolic extract of the plant shows a strong antioxidant activity comparable to that of the reference standards.