Marie-Claire Alain was one of the world's most respected organists, a leading teacher, and an expert on Baroque performing practices.

She came from a musical family. Her father was Albert Alain, the organist of the church of St Germain-en-Laye, who gave her her first lessons. Her brother Jehan (1913-1940), 15 years older than she, was by then already recognized as a highly talented organist who filled in for his father at the church as needed, and was showing talent as a composer. Her other brother, Olivier (b. 1918), eight years older, also was beginning to show talent.

It was a blow to both of them when Jehan was killed in action near the start of World War II. The war delayed Olivier's and Marie-Claire's musical education. She started at the Paris Conservatoire in 1944, studying harmony with Durufflé, counterpoint with Pié-Caussade, and organ with Marcel Dupré.

She won four first prizes while at the Conservatoire. After she graduated, she continued to win prizes in organ competitions, notably the Geneva International Competition and the Bach Prize of the Amis de l'Orgue in Paris.

She gave her first recital at St Merri, Paris. She was noted for her scholarship and devotion to stylistic authenticity. She deeply studied details of ornamentation and interpretation, developing a reputation as a specialist in the music of Bach and earlier composers. She was known for selecting music she considered appropriate for the individual instruments where she gave recitals: for instance, she favored Schnittger or Marcussen organs for Bach, and organs of Cliquot and builders of instruments in similar style for Couperin. The town of Lübeck awarded her its Buxtehude Prize for her services on behalf of Early German music.

However, she also frequently played later music, such as that of Franz Liszt, Olivier Messiaen, and her brother Jehan, and recorded organ concertos of C.P.E. Bach, Haydn, Mozart, Poulenc, Widor, and Vierne.

Besides touring around the world, she was in high demand as a teacher and lecturer. She recorded for her entire career with the French-based Erato label, making well over 200 releases. These include the complete organ music of J.S. Bach, Buxtehude, Bruhns, Couperin, de Grigny, Pachelbel, Mendelssohn, and César Franck. She earned more than 15 Grands Prix du Disque. She was a Commander of the Légion d'Honneur and a Commander of the Ordre National du Mérite. ~ Joseph Stevenson, Rovi