Luís Maria de Barros Serra Marques Guedes (born 25 August 1957) is a Portuguese lawyer and politician.
He held the position of Chairman of the Parliamentary Group of the Social Democratic Party, of which he has been a member since 1995.
He was deputy mayor of Cascais, and was responsible for the legal departments, municipal police, and civil protection.
He was also a member of the Municipal Assembly of Cascais and chairman of the Youth Institute.
He is a younger brother of Armando Marques Guedes, political scientist, anthropologist and former diplomat.