A comprehensive species review of the genera Gyrophaena Mannerheim and Eumicrota Casey is presented for New Brunswick, Canada. Twenty-four species of Gyrophaena are reported from New Brunswick including two new species, and two species of Eumicrota. Nineteen previously described species are newly recorded in New Brunswick, eight of which are newly reported in Canada. New species are: Gyrophaena meduxnekeagensis Klimaszewski & Webster, sp. n., and G. pseudocriddlei Klimaszewski & Webster, sp. n. New Canadian records are: G. chippewa Seevers, G. corruscula Erichson, G. dybasi Seevers, G. fuscicollis Casey, G. illiana Seevers, G. involuta Casey, G. laetula Casey, and G. lobata Casey. New records for New Brunswick: G. fuscicollis Casey, G. caseyi Seevers, G. chippewa Seevers, E. corruscula Erichson, G. criddlei Casey, G. dybasi Seevers, G. flavicornis Melsheimer, G. gaudens Casey, G. gilvicollis Casey, G. gracilis Seevers, G. illiana Seevers, G. involuta Casey, G. laetula Casey, G. lobata Casey, G. sculptipennis Casey, E. socia (Erichson), G. subnitens Casey, G. uteana Casey, and G. vitrina Casey. All species are documented by colour habitus images, black/white images of genital structures, and distributional maps. All female genital structures are presented and illustrated here for the first time. A key to the New Brunswick species is provided.