The relationships and taxonomy of the genus Thysanocarpus (Brassicaceae) are reassessed based on molecular phylogenetic analyses of nuclear ribosomal (ITS) and chloroplast (trnh-F) sequences and a critical re-examination of morphology and nomenclatural types. Based on these results, Thysanocarpus is well-supported as a member of tribe Thelypodieae, but no illuminating phylogenetic structure is found within the tribe. The independent origin of similar fruit morphology in Thysanocarpus and Athysanus is confirmed. Within Thysanocarpus,seven species are recognized: T. conchuliferus, T. curvipes, T. desertorum, T. erectus, T. laciniatus, T. radians, and T. rigidus comb. nov. Thysanocarpus laciniatus is found to have originated through hybridization. However, T. desertorum and T. rigidus, which have previously been included within T. laciniatus (as T. laciniatus var. hitchcockii and T. laciniatus var. rigidus,respectively), do not share that species' hybrid origin and are distinct both phylogenetically and morphologically. Within T. curvipes,five subspecies are recognized: T. curvipes subsp. amplectens comb. nov., T. curvipes subsp. curvipes, T. curvipes subsp. elegans comb. nov., T. curvipes subsp. longistylus comb. nov., and T. curvipes subsp. eradiatus comb. nov. Thysanocarpus curvipes subsp. elegans and T. curvipes subsp. longistylus form clades in ITS and/or trnL-F cladograms as well as showing morphological distinction. The remaining three subspecies are recognized based on a combination of morphology and geography.