This paper reports the species of Macrochiridothea occurring up to now on the continental shelf of southern Brazil. Two species are new to science: M. marcusi sp. n. and M. lilianae sp. n.. M. stebbingi Ohlin, 1901, is the third species reported for the area. The genus now comprises 8 species. A diagnosis for the genus, as well as for alI the species is given, together with comprehensive illustrations to permit prompt recognition of the species. Secondary sexual dimorphism is reported for the first time in the genus. A elassification key based on adults is furnished, and remarks or eomments for eaeh speeies are made. The geographie range for the genus has been considerably extended to the north, to about Lat. 23º07'S. General ecological and zoogeographieal remarks are made.