The endemic North American vaejovid scorpion subfamily Syntropinae Kraepelin, 1905, is redefined and its component genera revised, based on a simultaneous phylogenetic analysis of 250 morphological characters and 4221 aligned DNA nucleotides from three mitochondrial and two nuclear gene markers. Tribe Stahnkeini Soleglad and Fet, 2006, is removed from Syntropinae. Tribe Paravaejovini Soleglad and Fet, 2008, and subtribe Thorelliina Soleglad and Fet, 2008, are abolished: Paravaejovini Soleglad and Fet, 2008  =  Syntropinae Kraepelin, 1905, syn. nov.; Thorelliina Soleglad and Fet, 2008  =  Syntropinae Kraepelin, 1905, syn. nov. Eleven genera, six newly described, are recognized within Syntropinae: Balsateres, gen. nov.; Chihuahuanus, gen. nov.; Kochius Soleglad and Fet, 2008; Konetontli, gen. nov.; Kuarapu Francke and Ponce-Saavedra, 2010; Maaykuyak, gen. nov.; Mesomexovis, gen. nov.; Paravaejovis Williams, 1980; Syntropis Kraepelin, 1900; Thorellius Soleglad and Fet, 2008; Vizcaino, gen. nov. Hoffmannius Soleglad and Fet, 2008, is abolished: Hoffmannius Soleglad and Fet, 2008  =  Paravaejovis Williams, 1980, syn. nov. Lissovaejovis Ponce-Saavedra and Beutelspacher, 2001 [nomen nudum]  =  Paravaejovis Williams, 1980, syn. nov. Ten species, formerly placed in Hoffmannius, are transferred to Paravaejovis: Paravaejovis confusus (Stahnke, 1940), comb. nov.; Paravaejovis diazi (Williams, 1970), comb. nov.; Paravaejovis eusthenura (Wood, 1863), comb. nov.; Paravaejovis flavus (Banks, 1900), comb. nov. [nomen dubium]; Paravaejovis galbus (Williams, 1970), comb. nov.; Paravaejovis gravicaudus (Williams, 1970), comb. nov.; Paravaejovis hoffmanni (Williams, 1970), comb. nov.; Paravaejovis puritanus (