Two new styryl lactones, 9-deoxygoniopypyrone [1] and 7-epi-goniofufurone [3], and a known styryl lactone, goniodiol [5], were isolated from the stem bark of Goniothalamus giganteus. The structures were elucidated by ir, ms, 1H-nmr, 13C-nmr, and 1H-1H COSY spectra; the relative configurations were determined by X-ray crystallographic analysis. Unlike goniopypyrone [2] and goniofufurone [4], neither of the new styryl lactones 1 and 3 showed significant bioactivities to human tumor cells. However, goniodiol [5] showed significant and selective cytotoxicity against human lung tumor cells (A-549).