In Fennoscandia the highest number of Nemoura species (6) occurs in the north. Three species, Nemoura arctica, N. sahlbergi and N. viki, are restricted to the north. Three other species occur throughout much of Fennoscandia, while in the south there are four and in the costal areas in the west only a single species. Nymphs of the seven species of Nemoura occurring in Fennoscandia are described. The first instar nymphs of five of the species have also been examined. A key for species identification of nymphs is given and the nymphs of Nemoura viki Lillehammer and N. sahlbergi Morton are included in a key for the first time.