Organic extracts representing 48 species included in 30 families of Costa Rican tropical plants were evaluated for their ability to neutralize hemorrhagic activity induced by the venom of the snake <span name="style_italic">Bothrops asper</span>. A bioassay in mice was used, based on intradermal injection of either venom or venom-extract mixtures followed by the measurement of hemorrhagic areas. Total inhibition of hemorrhage was observed with the ethanolic, ethyl acetate and aquous extracts of <span name="style_italic">Bursera simaruba</span>, <span name="style_italic">Clusia torresii</span>, <span name="style_italic">C. palmana</span>, <span name="style_italic">Croton draco</span>, <span name="style_italic">Persea americana</span>, <span name="style_italic">Phoebe brenesii</span>, <span name="style_italic">Pimenta dioica</span>, <span name="style_italic">Sapindus saponaria, Smilax cuculmeca</span> and <span name="style_italic">Virola koschnyi</span>. Chemical analysis of these extracts identified catequines, flavones, anthocyanines and condensated tannins, which may be responsible for the inhibitory effect observed, probably owing to the chelation of the zinc required for the catalytic activity of venom’s hemorrhagic metalloproteinases.. Chemical analysis of these extracts identified catequines, flavones, anthocyanines and condensated tannins, which may be responsible for the inhibitory effect observed, probably owing to the chelation of the zinc required for the catalytic activity of venom’s hemorrhagic metalloproteinases.