A new subfamily of braconid wasps, the Mendesellinae, is proposed and described. It is represented by two genera and nine species, all newly described: Mendesella gen.n., type species M.amazonica sp.n., M.braziliensis, sp.n., M.magna sp.n., Epsilogaster gen.n., type species E.bicolor sp.n., E.braziliensis sp.n., E.dureno sp.n., E.palenque sp.n., E.tico sp.n. and E.panama sp.n. The phylogenetic relationships among the subfamilies of the 'microgastroid assemblage' of Braconidae are reviewed and analysed, to clarify the status and relationships of the new subfamily.