We analyzed the feeding ecology of four Thoropa miliaris (Anura, Cycloramphidae) populations from the Atlantic Rain Forest in Brazil. The diet was composed mostly of invertebrates, especially ants, beetles, grasshoppers, caterpillars, and spiders. Plant consumption was considered incidental because of its low frequency. Ants were the most frequent (range 70–100%) and numerous (range 54.9–63.8%) dietary items. In terms of volume, ants were the principal item at two localities (26.1% and 47.6%), being also important items for the other two areas (19.3% and 21.9%). Grasshoppers (20.1%) and beetles (22.8%) had the largest volume for two populations. There was a significant relationship of prey size and volume with frog jaw width in three of the four areas. Only in one area was this relationship not found, probably because of the high frequency with which small ants and termites were ingested. Many of the dominant prey taxa of T. miliaris were similar to those of other rain-forest frogs.