Four nematode species of the Comesomatidae from the Strait of Magellan and the Beagle Channel, Chile, are described as new to science. Comesoma hermani n. sp. can be separated from similar species, Conesoma bermudense Jensen & Gerlach, 1977, Comesoma minimum Chitwood, 1937 and Comesoma chilense Jensen & Gerlach, 1977 by the difference of body length, cephalic setae length, the ratio of the subcephalic setae to cephalic setae length and the ratio of spicule to anal body diameter. Dorylaimopsis magellanense n. sp. is identified by the lateral differentiation of 3-4 longitudinal rows of enlarged dots, the curved spicules are prominently jointed and with a ventral protrusion. Hopperia beaglense n. sp. could be easily recognised by both the rounded tail tip and anterior head end which differs from all the species of this genus except H. dorylaimopsoides (Allgen, 1959), which has, however, a smaller de Man ratio 'a' and reflexed ovaries. Hopperia arntzi n. sp. has a shorter body length which differs from the closest species, Hopperia americana Ward, 1984 and Hopperia muscatensis Warwick, 1973. Furthermore, the de Man ratio 'a' is different between our specimens and the other two species. An identification key to all known species of the genus Hopperia is provided.