Abstract
Four species of bat-fleas from Hokkaido and their hosts are studied. They are Nycteridopsylla nipopo from Murina aurata ussuriensis, Ischnopsyllus (Ischnopsyllus) elongatus from Noctula lasiopterus aviator, Ischnopsyllus (Ischnopsyllus) obscurus from Vespertilio superans, and Ischnopsyllus (Ischnopsyllus) needhami from Vespertilio superans. The occurence of I. obscurus in the north-eastern part of Hokkaido is recorded here for the first time.
