Crayfishes from 81 sites in New England yielded six species of branchiobdellidans — Bdellodrilus illuminatus, Cambarincola fallax, C. mesochoreus, C. philadelphicus, Pterodrilus missouriensis, and Xironogiton instabilis. This is the first report of the distribution of branchiobdellidans across the region. The Royal Ontario Museum, Toronto, Ontario, Canada, supplied branchiobdellidans, subsequently identified as C. mesochoreus, that had been removed from the gills of preserved marine crabs, Cancer borealis and Callinectes sp., reportedly collected from the Gulf of Maine, USA. Over 100 specimens of Hyas araneus, Cancer irroratus, C. borealis, and Carcinus maenas were collected at irregular intervals since 1978 from the coasts of northern Massachusetts, and Damariscotta estuary, Maine, USA and St. Andrews, New Brunswick, Canada, in an unsuccessful attempt to find a marine branchiobdellidan.