The Department of Ñeembucú is one of the least well-documented areas of eastern Paraguay, and the flora is composed of a mixture of forest and Chaco elements. Regions like Ñeembucú are often considered of lower diversity and interest that more forested regions; this results from both actual species richness figures and from under-collecting due to perception as uninteresting. We present here a checklist of the vascular plants of Ñeembucú, which includes 676 taxa (including subspecies and varieties) in 100 families and 374 genera. Four hundred and fifty seven (457) of these are new records for Ñeembucú and of these, 4 are new published records for Paraguay. Synonyms, distribution details within Paraguay and a voucher specimen or literature record are provided for each taxon, and a brief analysis of the diversity and importance of the flora is presented.