Genetic and morphological variation in two species of Euphorbia, Jeju island endemic E. fauriei and widespread E. pekinensis, was investigated using starch gel electrophoresis and numerical analysis. The high genetic identity between the two species and a significant number of unique alleles such as PGI-1^c, MDH-2^b, 6PGD-1^c, GA3PD-1^a and ADH-1^c in E. fauriei suggest that they may recently be originated from a common ancestor rather than the progenitor-derivative relationships. The higher level of genetic diversity in E. fauriei is unusual of species with limited geographic distribution. The relatively high levels of genetic diversity found among populations of E. fauriei indicates that the Jeju island may play an important refuge during the Pleistocene glaciation.