The extreme south of Madagascar is noted for the endemism of its marine biota, notably molluscs. Six new species of Muricidae Rafinesque, 1815 are described in the present paper; three in the subfamily Muricinae Rafinesque, 1815: Chicoreus (Triplex) kantori n. sp., Naquetia manwaii n. sp. and Dermomurex (Dermomurex) charlesi n. sp.; two in the subfamily Muricopsinae Radwin & D'Attilio, 1971: Favartia (Favartia) tantelyi n. sp. and Favartia (Pygmaepterys) fournierae n. sp.; and one in the subfamily Rapaninae Gray, 1853: Semiricinula bozzettii n. sp. Similar species from Madagascar and from other regions are compared and illustrated. The radula of Naquetia manwaii n. sp. and of Semiricinula bozzettii n. sp. are illustrated.