Two recent faunistic surveys in the Brazilian Atlantic Forests region, the PROFAUPAR and the Biota/FAPESP Program, have provided important material for the discovery of new taxa from Brazil. We describe herein four new species of robber-flies of the genus Oidardis (O. falcimystax
sp. n., O. fontenellei
sp. n., O. maculiseta
sp. n. and O. marinonii
sp. n.), including illustrations and details on male hypopygia and female genitalia. A distribution map and a key to the species of Oidardis from the Brazilian Atlantic Forests region, including O. triangularis (Hermann), 1912, are also provided.