Scathophaga stercoraria has been used for a large number of studies in animal ecology and evolution. Morphological phylogenetic work on the relationships among flies of the family Scathophagidae in general, and the genus Scathophaga in particular, has led to limited or incomplete conclusions. We addressed these relationships by sequencing 810 base pairs (bp) from the mitochondrial cytochrome oxidase subunit I (COI) gene and 738 bp of the mitochondrial cytochrome b (Cyt b) gene in 16 species of Scathophagidae. Phylogenetic analysis of these two protein-coding genes allows us to resolve relatively well the relationships within the genus Scathophaga, using both separate and combined (COI + Cyt b) data. Most of the phylogenetic trees generated by our data support the following relationships:(((S. analis + S. inquinata) + S. lutaria) + S. cineraria + (S. taeniopa + S. suilla + S. incola) + S. furcata + S. tropicalis). The most noteworthy findings are that (i) S. obscura and S. tinctinervis, which were formerly placed in the genus Coniosternum, form a sibling species cluster; (ii) S. taeniopa and S. suilla, which are morphologically very similar species, are clearly distinct taxa; (iii) S. analis, considered a doubtful species in the Catalogue of Palearctic Diptera, could be a synonym of S. inquinata; and (iv) the South American S. tropicalis and the Old World S. stercoraria are not sister-species.