Forty-eight species of Aleocharinae are newly reported from New Brunswick, bringing the total number of species known from the province to 149. Two of these species, Ocyusa asperula Casey and Myllaena kaskaskia Klimaszewski, are newly recorded for Canada. Additional locality data are presented for nine species recently recorded from the province. Collection and bionomic data for all these species are presented and discussed. Colour habitus images are presented for all species included in this paper and genital images are presented for closely related Myllaena kaskaskia Klimaszewski, M. procidua Casey and M. vulpina Bernhauer. Photographs of the male genitalia of M. procidua are presented for the first time. The female spermatheca, tergite and sternite eight of Amarochara formicina Assing are illustrated for the first time.