Stockwell (1989), in an unpublished revision, suggested the elevation of subfamily Urodacinae to the family rank, and considered Heteroscorpioninae a subfamily of Ischnuridae. Heteroscorpioninae was formally elevated to the family rank by Lourenço (1996a), and Urodacinae, by Prendini (2000). As a result of a detailed cladistic analysis, Prendini (2000, 2003b) considered families Heteroscorpionidae and Urodacidae to be sister groups, although an al-ternative topology was available. Soleglad & Fet (2003b) questioned the results of Prendini (2000) but nevertheless retained the monophyly of Heteroscorpion and Urodacus pending more detailed analysis; they recognized two valid monotypic subfamilies, Heteroscorpioninae and Urodacinae, under Urodacidae. Our present detailed cladistic re-analysis of Heteroscorpion and Urodacus confirms the phylogeny proposed by Stockwell (1989), which also is the “suboptimal” topology of Prendini (2000, 2003b). The family Urodacidae is abolished; the subfamily Urodacinae is transferred to Scorpionidae. Hemiscorpiidae Pocock, 1893 is accepted as a senior synonym of Liochelidae, and Hormurinae Laurie, 1896, as a senior synonym of Liochelinae. The subfamily Heteroscorpioninae is transferred to Hemiscorpiidae. As a result, the superfamily Scorpionoidea currently includes three families: Bothriuridae (with two subfamilies, Bothriurinae and Lisposominae), Hemiscorpiidae (with three subfamilies, Hemiscorpiinae, Heteroscor-pioninae, and Hormurinae), and Scorpionidae (with three subfamilies, Diplocentrinae, Scorpioninae, and Urodacinae).