An updated checklist of 50 species of mosquitoes found in Montana is presented and includes 2 new records (Aedes niphadopsis and Anopheles walkeri) that can be added to the 2005 state list by Darsie and Ward. The results of a statewide mosquito surveillance program, conducted annually from 2004 to 2015, facilitated the establishment of an abundance rating of the species in the state and expanded the known geographic range for Coquillettidia perturbans, Ae. nigromaculis, and Culiseta minnesotae.
Keywords: Checklist; Montana; distribution; mosquitoes; new record.