This is a list of the counties in the U.S. state of Montana.

Montana has two consolidated city-counties—Anaconda with Deer Lodge County and Butte with Silver Bow County.

The portion of Yellowstone National Park that lies within Montana was not part of any county until 1978, when part of it was nominally added to Gallatin County, and the rest of it to Park County.

Montana's postal abbreviation is MT and its FIPS state code is 30.

The Federal Information Processing Standard (FIPS) code, which is used by the United States government to uniquely identify counties, is provided for each county.