Sironidae, the first described family of Cyphophthalmi, is among the least understood phylogenetically. After examining recent collections across their distribution range, we provide the first comprehensive treatment of Sironidae by including molecular data from most of the known species, and all genera except for the monotypic Odontosiro Juberthie, 1961. We also revisit the male genitalic morphology for most genera by using confocal laser scanning microscopy and provide descriptions of five new species belonging to Iberosiro de Bivort & Giribet, 2004 (monotypic until now), Paramiopsalis Juberthie, 1962 and Siro Latreille, 1802. While the monophyly of Sironidae remains poorly supported using traditional Sanger-based markers, with the Mediterranean Parasiro Hansen & Sørensen, 1904 and the Japanese Suzukielus Juberthie, 1970b sometimes branching basally with respect to the other sironids, the remaining genera form a well-supported Laurentian/Laurasian clade. This group divides into a Western European/North American clade of Siro and the remaining genera, Iberosiro, Paramiopsalis and Cyphophthalmus Joseph, 1868. Iberosiro and Paramiopsalis form a well-supported clade from the NW corner of the Iberian Peninsula, while Cyphophthalmus is widespread in the Balkan region and Eastern Mediterranean. Finally, the following new taxa are described: Iberosiro rosae Giribet, Merino-Sáinz & Benavides, sp. nov., Paramiopsalis anadonae Giribet, Merino-Sáinz & Benavides, sp. nov., Paramiopsalis ramblae Benavides & Giribet, sp. nov., Siro ligiae Giribet, sp. nov., and Siro richarti Benavides & Giribet, sp. nov.