María Isabel Siewers (born October 22, 1950) is an Argentine classical guitarist. A pupil of María Luisa Anido, her international performance career began after winning the 2nd Prize at the Concours International de Guitarre de Paris in 1974. She has regularly toured, taught, and served in juries for international competitions throughout Europe, North and South America, Australia, and New Zealand. Isabel has occupied several teaching posts in Argentina and, since 1989, she has been head of a guitar department in the Mozarteum University of Salzburg, Austria.