Line 4 of the Saint Petersburg Metro, also known as Lakhtinsko-Pravoberezhnaya Line or Orange Line, is a rapid transit line in Saint Petersburg, Russia, which connects city centre with the south-east districts on the right bank of the Neva River. Despite its name, which literally means Lakhta–Right Bank Line, the line from its opening date had the stations on the left bank of the Neva River. Moreover, currently the line has not any stations near the Lakhta area. Opened in 1985, it is the shortest line in the system with the stations featuring a modern design. Since 1994, it has been officially designated "Line 4," but the original name is still often used in informal context.

The Saint Petersburg Metro is a rapid transit system in Saint Petersburg, Russia. Construction began in early 1941, but was put on hold due to World War II and the subsequent Siege of Leningrad, during which the constructed stations were used as bomb shelters. It was finally opened on 15 November 1955.