Analysis of a methanolic extract of Tagetes lucida leaves has resulted in the isolation of a new flavonol glycoside, quercetagenin 3,4'-dimethyl ether 7-O-beta-D-glucopyranoside (1), two new phenolic acids, 3-(2-O-beta-D-glucopyranosyl-4-methoxyphenyl)propanoic acid (2) and its methylester (3), and known flavonols, aromatic acids, and 7-methoxycoumarin. Using the DPPH degrees test, the extract and some of its constituents showed a significant free-radical-scavenging effect in comparison to alpha-tocopherol and standard flavonols.