Twenty-five genera and 32 species of Eocene shallow-marine ostracods from Madagascar were examined for taxonomy and palaeobiogeography. Eight new species – Paijenborchellina madagascarensis sp. nov., Neocyprideis polygonoreticulata sp. nov., Alciella irizukii sp. nov., Neomonoceratina afroangulosa sp. nov., Muellerina eocenica sp. nov., Stigmatobradleya hunti gen. et sp. nov., Uroleberis paranuda sp. nov., Xestoleberis renemai sp. nov. – and one new genus – Stigmatobradleya gen. nov. – are described. Eocene Malagasy ostracods showed a strong affinity to the Eocene East Tethyan fauna in Arab-Africa and Indo-Pakistan. They also showed certain affinity to the Eocene West Tethyan fauna in Europe. One species, Pokornyella lamarckiana sensu lato, showed a very wide Eocene geographical distribution, covering Europe, Indo-Pakistan, Arab-Africa, Japan and perhaps North America. These results indicate that the East African, Arabian, and Indo-Pakistan regions constitute the East Tethyan palaeobiogeographical sub-realm, with considerable faunal similarity found across the regions. This sub-realm extends to south-eastern Africa in the south and is a part of the broader Tethyan palaeobiogeographical realm with certain, but less, palaeobiogeographical similarity. The spatial extent of the Tethys palaobiogeographical realm sensu lato includes Asia-Oceania in the east and eastern America in the west. Based on our results, we suggest a need to update the scheme of global ostracod biogeographical division.