Three rainbow smelt Osmerus mordax with subcutaneous tumors were caught in estuaries at two locations in Nova Scotia and one location off Prince Edward Island. The tumors consisted of a well-circumscribed nodule or series of nodules surrounded by a thin layer of connective tissue containing melanocytes. The surrounding skeletal muscle fibers were often compressed. The tumors were identified as schwannomas, composed of spindle cells arranged in palisades, forming Antoni type A tissue, and less cellular Antoni type B tissue. In one case the nerves of origin of the tumor were compressed to one side of the tumor.