From the roots of Vismia guineensis 23 structurally related compounds were isolated and identified. Ten of them are new constituents, namely 3-O-(2-hydroxy-3-methylbut-3-enyl)-emodin (1); 3-O-(2-methoxy-3-methylbut-3-enyl)-emodin (2); 1, 8-dihydroxy-3-(2-methoxy-3-methylbut-3-enyloxy)-6-methylx anthone (3); 1,8-dihydroxy-3-geranyloxy-6-methylxanthone (4); 1, 8-dihydroxy-3-isoprenyloxy-6-methylxanthone (5); 1,8-dihydroxy-3-(3, 7-dimethyl-7-methoxyoct-2-enyloxy)-6-methylxanthone (6); 3-O-(E-3-hydroxymethylbut-2-enyl)-emodin (7); 3-O-(3-hydroxymethyl-4-hydroxybut-2-enyl)-emodin (8); 1, 8-dihydroxy-3-(E-3-hydroxymethylbut-2-enyloxy)-6-methylxa nthone (9); and 1, 8-dihydroxy-3-(3-hydroxymethyl-4-hydroxybut-2-enyloxy)-6- methylxantho ne (10). Their structures were established by means of EIMS and a combination of homonuclear and heteronuclear 2D NMR techniques. Furthermore, an in vitro preliminary screening of antimitotic activity of all the isolated compounds was also evaluated.