A chemosystematic study on euphorbiaceous plants in Korea has been performed by using phenolic constituents. The phenolic characteristics of subfamilies, genera and species were well distinguished from one another. Hydrolyzable tannins as constituents were considered to be a valuable taxonomic character in elucidating systematic relationships among the related taxa whereas flavonoids could be used in the classification of infraspecific taxa in this family. The phenolic fingerprints of each of the plants would be considered as a good tool to identify the species. In comparison with the morphological classification system, the chemical relationship supported the subfamilial system of Webster (1975) and the further division of Euphorbia sensu lato by Hurusawa (1954).