Abstract: On the basis of investigating and evaluating the circumscriptions of primitive angiosperms by different authors, in the present paper we proposed a new conception with 60 primitive families of angiosperms following our eight-class system of flowering plants. A phytogeographical study was carried out using these families as characters, and Thakhtajan’s floristic “regions” of the world as OTUs. As a contrast, we simultaneously conducted another data set including only 32 basal families according to molecular systematic studies during the recent years. The results by UPGMA analyses indicated that Eastern Asiatic Region is really very unique; it is closely related to North American Atlantic Region and Madrean Region of eastern and western North America, but has more characteristics similar to Indochinese Region. Additionally, the UPGMA trees showed that 4 circum-Pacific districts, e. Asia, e.& w. of N. America, partly tropical Asia, e. Australia,& sw. Pacific islands, tropical C. & S. America, are the areas of great concentration of primitive angiospermous families. This distribution pattern obviously relates to the birthplace and dispersal routes of angiosperms and the history of the Pacific Ocean.

Key words: Primitive angiosperms, Basal angiosperms, Phytogeography, Eastern Asiatic Region, Pacific