St. Mary's County Regional Airport (IATA: LTW, FAA LID: 2W6), also known as Captain Walter Francis Duke Regional Airport, is a public airport located in St. Mary's County, Maryland, United States, four miles (six km) northeast of the central business district of Leonardtown. The airport is also located 8 nmi (15 km) west of Naval Air Station Patuxent River. It is owned and operated by the St. Mary's County Board of County Commissioners.

St. Mary's County Regional Airport has been in operation since 1969. The airport was re-dedicated as the Captain Walter Francis Duke Regional Airport in 2000. It recently reverted to its original name.