The Chironomidae, or non-biting midges, of Illinois have been untreated since the early 20th century, and the high level of taxonomic flux in the family necessitates an update, particularly for a group with importance as bio-indicators of freshwater ecosystem health. Herein, 181 species of Chironomidae in 76 genera are recorded from the state of Illinois. Each species entry is annotated with the first Illinoisan record of the species. Two genera, Brillia Kieffer, 1913 and Prodiamesa Kieffer, 1906, are recorded for the first time from Illinois, as are three species: Xenochironomus xenolabis (Kieffer in Thienemann and Kieffer, 1916) (Chironominae); Brillia flavifrons (Johannsen, 1905) (Orthocladiinae); and Prodiamesa olivacea (Meigen, 1818) (Prodiamesinae)
