The article presents an update and analysis of the distribution data for the rare fern species, Botrychium virginianum (L.) Sw., in the North-West of European Russia. We confirm the species' presence in three localities in the Leningrad Region, although when the Red Data Book of the Leningrad Region was published (2018) there was no information on any remaining localities of the species. The article is illustrated by a map which shows the years of finding B. virginianum in all its localities in the North-West of European Russia. The ecology of the species in the new localities is analyzed and information about the number of plants is given. Analysis of the dynamics of the number of known B. virginianum localities since the mid-19th century shows an overall significant decline in North-West Russia, predominantly in the period from the 1940s to the 1980s. In the latest decades, the number of localities has increased. Similar changes in the number of localities are shown for Estonia. We analyze the possible reasons for the dynamics observed. The criteria for attributing this species to IUCN categories for regions of North-West European Russia have been updated.