Montana Highway 80 (MT 80) is a 67.172-mile-long (108.103 km) north–south state highway in the U.S. State of Montana. MT 80's southern terminus is at U.S. Route 87 (US 87), MT 3 and MT 200 in the community of Stanford and the northern terminus is at US 87 in the town of Fort Benton. The landscape is hilly and rural, and largely used for wheat farming; the road also passes through Arrow Creek Canyon and near the Highwood Mountains. Between Arrow Creek and Geraldine, MT 80 is roughly paralleled by the main line of Central Montana Rail.

Before receiving its current designation, Highway 80 was designated as Montana Secondary Highway 230.

County	Location	mi	km	Destinations	Notes
Judith Basin	Stanford	0.000	0.000	US 87 / MT 3 / MT 200 – Lewistown, Great Falls
Fergus	​	17.394	27.993	MT 81 east – Denton
Chouteau	​	64.560	103.899	S-228 south
	Fort Benton	65.193	104.918	S-386
		65.614	105.595	S-387 north
	​	67.172	108.103	US 87 / S-223 – Great Falls, Havre, Chester
1.000 mi = 1.609 km; 1.000 km = 0.621 mi