The structures of two new lignan constituents of Heliopsis scabra, helianthoidin and helioxanthin, have been determined by spectral and degradative work. The former is shown to be 2-angelyloxy-2-piperonyl-3-veratryl-2S,3S-γ-butyrolactone (I), and the latter 1-(3,4-methylenedioxyphenyl)-2-hydroxymethyl-7,8-methylenedioxy-3-naphthoic acid lactone (XVII).