Yosemite Mountain Sugar Pine Railroad, Heritage railroad in Sierra National Forest, California, US.

The Yosemite Mountain Sugar Pine Railroad is a 3 ft (914 mm) narrow-gauge heritage railway at 56001 State Route 41 in Fish Camp, about 5,000 ft up in the Sierra National Forest. Its 4-mile round trip follows part of the Madera Sugar Pine Lumber Company grade south through second-growth ponderosa pine and mixed conifer, with its only stop at a loop in Lewis Creek Canyon.

The railway follows the former route of the Madera Sugar Pine Lumber Company, which operated around 140 miles of track from the late 1800s until 1931 to transport logs. The line closed when the region's timber industry declined.

The name Sugar Pine comes from the local term for the Lambert pine. At the depot, the Thornberry Museum occupies a relocated 19th-century log cabin with exhibits on Sierra Nevada logging, and the Sugar Pine Trading Company sells railroad and Yosemite Valley history books. Visitors can also try gold panning.

Steam locomotives run in summer; in the off-season the "Jenny" railcars are used instead. The standard Logger Steam Train excursion takes about one hour, while evening dinner trains last around three hours. The depot is at 56001 State Route 41 in Fish Camp, at about 5,000 feet elevation. Passengers ride in open-air or covered cars.

Shay No. 10 was built by Lima Locomotive Works on 2 March 1928 for the Pickering Lumber Company and reached the West Side Lumber Company in 1934. Its tanks hold 4,500 litres of oil and 12,900 litres of water. The railroad bought it in 1961, and it opened the line to the public in 1966.