A remarkable diversity of new nonempidoid orthorrhaphan flies from the mid-Cretaceous of Myanmar (Late Albian–Early Cenomanian, ca. 99 Ma) is presented, including 28 species (all but one new) in 22 genera (13 new), and at least 12 families. Two families are new; three genera are unplaced in Tabanomorpha and one unplaced within Brachycera. Comparisons are presented between the amber taxa and extensive lithified taxa from the Jurassic and Cretaceous of eastern Laurasia.In Stratiomyomorpha: A new species of Zhangsolvidae has color patterns and body shape that apparently mimic Vespidae or other stinging aculeate wasps. Diverse new Xylomyidae and Stratiomyidae are described, the latter with male terminalia preserved in detail. In Tabanomorpha: The genus Athericites Mostovski et al. is synonymized with Palaepangonius Ren, and a new species of Galloatherix Nel is described in which the female proboscis is much longer than that of the male. All three genera were attributed to Athericidae, but the amber species reveal they are more basal tabanomorphs. Described are a new genus of stem-group Tabanoidea and a new species of Cratotabanus Martins-Neto and Kucero-Santos (Tabanidae), previously known from the Cretaceous of Brazil and New Jersey. In Nemestrinoidea: Three species of Hirmoneura Meigen are the first Nemestrinidae known from amber; one species has long cerci typical of Recent species of the genus. A new species of the Mesozoic family Rhagionemestriidae reveals this family is closely related to Acroceridae, not Xylophagidae as previously proposed. In Archisargoidea: A new species of Tethepomyiidae is described, the family known only in Cretaceous amber from New Jersey, Spain, and Myanmar. In Asiloidea: Three new species and genera of Bombyliidae are described, two of them with abdominal setal “baskets” distinctive to females of higher bombyliids. A fourth new asiloid genus is a probable stem-group bombyliid. The recently described Pseudorhagio Zhang et al., is transferred from Tabanomorpha to Bombyliidae. The male of a new species of Burmapsilocephala Gaimari and Mostovski (Apsilocephalidae) has terminalia very similar to that of Evocoa (Evocoidae: Recent, Chile), corroborating close relationship of the two families. In Families incertae sedis: A new species of Hilarimorphites Grimaldi and Cumming (Apystomyiidae) is described, the family known only in New Jersey and Burmese amber and the Recent fauna of California, and a sister group to either Cyclorrhapha or Eremoneura. Mysteromyiidae and Eucaudomyiidae, new families, are described, based on highly modified species with vestigial mouthparts, reduced venation, and unique specializations.Discussion is presented on some morphological features in fossil and Recent Brachycera that have apparent phylogenetic significance but are rarely discussed. This study adds further data to the phenotypic diversity, geological history, and biogeography of a major radiation.