This first contribution to knowledge of Naididae and Tubificidae of Guatemala, El Salvador, and Nicaragua reports the occurrence of 17 forms. Of these, Nais communis, N. elinguis, N. pardalis, Dero digitata, Pristina longiseta, Limnodrilus hoffmeisteri and L. udekemianus are cosmopolitan species, while Dero pectinata and Allonais inaequalis are widely distributed in the southern hemisphere. Slavina evelinae and Aulodrilus cernosvitovi were previously known only from South America and occurred here in fertile lowland lakes, environments having the greatest similarity to waters of the regions from which they were originally recorded. The specific identity and affinities of the six other forms must await further collections and study. Descriptions, as far as is possible from whole mounts, have been included here to facilitate their recognition in future work. Surprisingly, no mature specimens of the cosmopolitan Tubifex tubifex (Muller 1774) occurred in these collections. In fact, of the 875 specimens examined in this study, only one immature tubificid from L. Amatitlan (Loc. 4), resembled T. tubifex. Its absence would indeed be surprising; T. tubifex is known from many localities in North America and has been collected in Brazil (Marcus 1942), and from Bogota, Columbia by this author. In many parts of the world T. tubifex, “with Limnodrilus hoffmeisteri is the commonest tubificid in all sorts of habitats” (Brinkhurst 1963). If T. tubifex does occur in Central America, the scarcity in these collections of specimens even resembling it, suggests that it is unusually rare.