Abstract: The present paper has at the outset briefly reviewed the previous work done on the genus Cyrtomium Presl by Christensen¹⁾, Tagawa²⁾ and Ching³⁾ and then pointed out that the present study, based on extensive material as citated under respective species, resulted in recognizing 59 species for the genus, of which 42 are described for the first time. However, it may be pointed out that, because of the frequent occurence of a series of morphologically intermediate forms, it seems to be apparent that hybrids may be rampant, especially among the species of the Subseries Fortuneana, and that a number of clearly definable are here tentatively described as forms or varieties under the related species, pending further haryological studies. Geographically, the genus is almost exclusively confined to China and Japan, with one outlying species, C. micropteron (Kze.) Ching, in Southern India and East Africa. Cytologically, the genus so far studied by Manton¹⁾ and the present writer (unpublished) has revealed that the species of the Series Fortuneana are apogamous triploids, but it is believed that diploids may exist in the members of the Series Nephrolepioidea, for which study is now in progress. Systematically, the genus Cyrtomium is no doubt very closely related to Polystichum Roth, especially to the Sect. Achroloma Tagawa from which it seems to be directly derived. According to the types of venation, pinnation of frond-end, and the margin of the pinnae (i.e. whether it is entire or serrate), the genus may be divided into two series, each with two subseries. In the old Chinese medical books, Cyrtomium fortunei and its allies are said to bea useful drug long used as antiseptics by the Chinese people.