The zooplankton in South American saline waters is mainly dominated by copepods at salinities lower than 90 g/l, whereas at salinities above 90 g/l Artemia sp. is totally dominant. The aim of the present study is to analyse the salinity range of halophilic copepods on the basis of a literature review for South American saline inland waters. The calanoid Boeckella poopoensis Marsh, 1906, is widespread on the South American Altiplano and southern Argentinian plains, and in southern Patagonian shallow ponds. In the upper part of the salinity range, 20-90 g/l, B. poopoensis is the only copepod in the zooplankton of southern Patagonian and Altiplano shallow lakes. In the salinity range 5-20 g/l B. poopoensis may co-exist with B. palustris (Harding, 1955), two cyclopoids and an harpacticoid, and at salinities lower than 5 g/l it may co-exist with an even wider range of copepod species. Ecological and biogeographical aspects are also discussed