The Cathedral's Grand Orgue , built in 1887 by the prestigious French firm Aristide Cavaillé-Coll, was inaugurated on October 5, 1887, by Alexandre Guilmant.  It has been suggested that Marcel Dupré is the person most responsible for the evolution of the instrument, which is still one of the largest in Paris:  it was Dupré who acted as consultant, first in 1922, again in 1930, then again in the 1950's, with Maurice Duruflé.  The latest restoration was completed in 1993 by the organ firm of Bernard Dargassies with the generous support of the Paulé Foundation and other Cathedral members.  The organ was re-dedicated on February 21, 1993, and re-inaugurated on May 18, 1993, by Marie-Madeleine Duruflé, and on May 30, 1993, by Marilyn Keiser. 

Since the 1993 restoration project, the organ has had a powerful and positive effect upon Cathedral services.  In addition, many visitors and visiting organists have commented on the beauty and personality of its tone and the variety of sounds possible.  Monthly auditions d'orgues, given on the afternoons of the third Sunday of each month, immediately before Solemn Evensong sung by the Choir, attract a loyal group of admirers. 

A small, mechanical-action organ, built by the French firm of Erwin Müller, was placed in the rear gallery in 1970.  In 1993 Monsieur Dargassies modified this organ and made it part of the Chancel Organ: the Cathedral's Grand Orgue is actually one organ in two parts.  The Grand Choeur division "pulls the sound of the main organ into the nave of the Cathedral, and the two act as one," in the words of Canon Precentor Edward J. Tipton, Organist and Choirmaster.