Cristina Theoduloz, Patricia Pacheco and Guillermo Schmeda-Hirschmann Facultad de Recursos Naturales, Departmento de Ciencias Biológicas, Universidad de Talca, Casilla 747, Talca, Chile.Twenty-one Myrtaceae collections belonging to 10 species, 5 of which are used in Chilean folk medicine, were assayed for inhibitory activity towards the enzyme xanthine oxidase. Most leaf and stem extracts were devoid of activity or showed a weak inhibitory effect. Chilean ethnobotanical data on the species arc linked to the astringent properties of Myrtaceae and their use for treating wounds and diarrhea. The results show the advantage of using proper plant selection criteria when searching for new drugs to treat human gout.