The complete holdings of Macrobdella species at the Smithsonian's National Museum of Natural History were examined and the identity of 4 specimen lots were redetermined. One of these lots was redetermined as Macrobdella sestertia and represents the first report of this species from New Hampshire. Prior to this report, this species was only known from a few occurrences in eastern Massachusetts and Maine. This is also the first report of this species to be found in sympatry with Macrobdella decora, a more common congener with a widespread distribution.