The natural gas industry of Montana became important with the development of the Cedar Creek (Baker-Glendive) anticline in 1915, but for 6 years development was slow. Since 1926 the development of the fields has been accompanied by the construction of pipe lines to other than local markets. As of August 1, 1933, there are 11 producing fields, 10 localities at which gas has been discovered but generally not produced excepting for local use, and several promising untested areas. This paper describes briefly the stratigraphy and geologic structure of the state. Synoptic descriptions of the important gas fields are given, covering the following subjects: producing horizon, geologic structure, proved area, number of wells, depth of wells, annual production, and total productio . The controversial question of the gas reserve of the fields is not discussed. The gas fields briefly mentioned in this paper are: Cedar Creek (Baker-Glendive), Border-Red Coulee, Bowdoin, Bowes, Boxelder, Cutbank, Dry Creek, Hardin, Kevin-Sunburst, Lake Basin (Big Lake anticline), and Whitlash.