The chromosome numbers of the four species (Hosta kiyosumiensis, H. sieboldiana, H. hypoleuca and H. caput-avis) were 2n=60. The karyotypes of these species were as follows: the 60 chromosomes were in 30 pairs, which could be classified into the three groups of four pairs of large chromosomes, two pairs of medium ones, and 24 pairs of small ones. Details in each of the three groups differed according to species. In the clone of H. sieboldiana obtained in Kyoto, the karyotype was the one original to this genus: four pairs of large chromosomes with terminal or subterminal primary constriction, and two pairs of medium chromosomes of which one had satellites. In the clone of the same species from Hirosaki, however, the karyotype differed from the above in that there were no satellites. In H. caput-avis, karyotypes differed according to the clones used, variation being found in the positions of primary constriction in the large and medium chromosomes. Of the four pairs of large chromosomes of H. kiyosumiensis and H. caput-avis, one pair were satellite chromosomes with submedian primary constriction. It can probably be inferred that these chromosomes derived from large chromosomes with terminal primary constriction.