Lissorchis nelsoni (Trematoda: Lissorchiidae) is described from the intestines of the spotted sucker, Minytrema melanops (Rafinesque) from the Wolf River in central Wisconsin and from Navigation Pools 8 and 9 of the upper Mississippi River near La Crosse and Genoa, Wisconsin. It is readily distinguished from all other species of Lissorchis by a combination of its surface structures, massive cirrus sac bent at an angle (often almost an inverted “L”), bipartite seminal vesicle, large acetabulum, a trilobed ovary, its vitellarium, and a type B uterine configuration, of which the cirrus sac is perhaps the most useful for stained material. It is morphologically similar to Lissorchis mutabile in having a similar size and body shape, similar number and arrangement of vitelline follicles, and a distinctly trilobed ovary. In addition to differences in the cirrus sac morphology, it also differs from L. mutabile in having an extensively coiled uterus that extends on both sides of the hindbody.