Burmaculex antiquus new genus, new species, is described from a single partially preserved adult female in Burmese amber. The fossil has several plesiomorphic features, indicating that it is the sister group of all other fossil and extant Culicidae: a relatively short proboscis, the palpi extending beyond the apex of the proboscis, a clypeus with several setae, and the palpus without scales. Antennal and mouthpart structure suggest the female of this fossil species was a vertebrate blood feeder. The age of Burmese amber has been estimated as between Upper Albian to Turonian, 100–90 million years ago but the origins of the Culicidae are likely significantly older. The sister group of the Culicidae are the Chaoboridae, known as Jurassic fossils, and the Culicidae therefore must be equally as old. Although fossil adults of the two families may not be distinct at this early stage of evolution, the immatures would likely provide distinguishing features.