A reevaluation of South American oligochaetes produced 871 known species. Megadrile earthworms have rates of endemism around 90% in South America, while Enchytraeidae have less than 75% endemism, and aquatic oligochaetes have less than 40% endemic taxa in South America. Glossoscolecid species number 429 species in South America alone, a full two-thirds of the known megadrile earthworms. More than half of the South American taxa of Oligochaeta (424) occur in Brazil, being followed by Argentina (208 taxa), Ecuador (163 taxa), and Colombia (142 taxa). Present diversity counts of Oligochaeta are still substantially underscored. Surveys of Enchytraeidae in native forests in São Paulo 30 years ago produced a 100% yield of new species, while this group is still unregistered in the whole northeast region of Brazil. There is clearly much basic research to be done on oligochaetes in South America.