South Dakota Highway 27 (SD 27) is a 42.639-mile (68.621 km)[1] state highway in Day and Marshall counties in South Dakota, United States, that connects Pierpont, Langford, and Britton.

SD 27 begins at an intersection with U.S. Route 12 (US 12) southeast of Andover, in the central part of Day County.

An intersection with the western terminus of Main Street leads to the business district of the town.

Just north of an intersection with the western terminus of 3rd Street, it leaves the city limits of Pierpont.

At an intersection with the eastern terminus of Main Street, it turns right and travels to the east.

Just west of 7th Avenue, they cross over the railroad tracks of BNSF Railway from before.

At an intersection with 429th Avenue, the two highways split, with SD 27 resuming its path to the north.