Studies on the chemical constituents from the stem bark of Grewia optiva have led to the isolation of two new compounds, grewialin (1) and optivanin (2), along with three known constituents which were hitherto unreported from this species. The structures of the new constituents have been elucidated by spectral studies including 1D and 2D NMR experiments (HSQC, HMBC, COSY, NOESY and J-resolved) as well as HR EI-MS spectroscopic data analysis, as 2S*-(3-hydroxy-4-methoxyphenyl)-3R*-methyl-2H-[1,4]-dioxin [2,3]-chromen-7(3H)-one (1); a coumarinolignan and 3-hydroxy-1-(3-hydroxy-4-methoxyphenyl) propan-1-one (2). The known compounds were identified as β-sitosterol, stigmasterol and lupeol by comparing their spectral data with those reported in the literature.