The species of Finnish watermites (Acari, Hydrachidia and Halacaroidea) are listed, and their occurrence in the biogeographical provinces shown. The list is based on publications, on unpublished data known by the authors, and on a private collection (of Pauli Bagge). The list consists of 139 Hydrachnidia and 9 Halacaroidea species, which are
mainly limnetic or lotic. Brackish waters and the family Halacaridae have remained little studied
