Some actinolaimid nematode species belonging to the genera Egtitus Thorne, 1967 and TrachypleurosumAndrássy, 1959 are described or redescribed from Costa Rica. Egtitus costaricae sp. nov. is distinguished from the related species,E. biformis Andrássy, 2012, E. neocyatholaimus (Kreis, 1936) and E. proximus (Yeates, 1973), by the wide lip region (21–23 vs 15–17 μm) and the low number of the male supplements (6–8 vs 9–13). The Costa Rican specimens of Trachypleurosumvenezolanum Coomans, Vinciguerra & Loof, 1990 correspond well with the original description. Three probable new species, viz.Egtitus sp. 1, Egtitus sp. 2 and Trachypleurosum sp. are also described on the basis of male specimens, but due to lack of femalesthey are not provided with species names. In the Appendix five genera and forty-two species of free-living nematodes describedas new to science from Costa Rica are listed.