The leaves and bark of fifteen species of Mexican Anacardiaceae were analyzed by paper and thin layer chromatography for the presence of toxic phenols such as catechols, resorcinols and biflavonoids. Based on the results of this and previous studies, toxic phenols are present in fifty-two species belonging to twenty-seven genera in Anacardiaceae. The majority of species contain toxic catechols, a few species contain toxic resorcinols and sixteen species contain biflavonoids. Genera from the basal group in Anacardiaceae, including Spondias and allied genera lack biflavonoids. Biflavonoids are present in the rest of the genera of Anacardiaceae.