State Route 242 (SR 242) was an east–west state highway in the west-central portion of Ohio. The western terminus of the route was at U.S. Route 127 approximately 5 miles (8.0 km) north of Greenville. Its eastern terminus was at a T-intersection with SR 121 adjacent to Darke County Airport about 1.5 miles (2.4 km) southwest of Versailles.