Alloglossidium hirudicola sp. n. is described from adult specimens recovered from the ceca of leeches, Haemopis sp., purchased from a commercial source. It differs from A. corti (Lamont, 1921) Van Cleave and Mueller, 1934, and from A. geminus (Mueller, 1930) Van Cleave and Mueller, 1934, in having shorter ceca, smaller cirrus pouch, and in distribution of cuticular spines.