All of the documents from the Music Section of Olaeta Ballet’s heritage are closely related to its performances. The organisation and safekeeping of the archive corresponds directly to the business part of the Olaeta Ballets. Víctor Olaeta carefully kept this archive using great criteria thanks to his double professional training as a dancer and as a musician.

This Section’s content allows us to know in great detail the activities of Segundo Olaeta and his group Elai-Alai, from which we could highlight the high proportion of choral music.

A significant part of the content consists in band music, relating to the activities of both the father and the son and of conductors of this type of instrumental ensembles. The two types of documents in this Section, scores and recordings, set the performances of the Olaeta Ballets, albeit in a different way: The scores on the one hand define the musical and choreographic form prior to the performances; the recordings on the other hand fix the sonorous aspects for their subsequent conservation and assessment.

This content bears witness to the intense collaboration with the best composers from the Basque Country like Guridi, Franco, Escudero, Arámbarri, Padre Donostia, Olaizola or  Zubizarreta. 

The recordings made during the tours in the United States of America leave a record of the work of the Olaeta Ballets and the musicians who accompanied them (the txistulari Boni, the trikitilari Julio Fernández and the albokari Txilinbrin) as cultural ambassadors of the Basque Country.

The content also documents the introduction of classical dance into the Basque Country, not only the best-known repertoire from the 19^th and 20^th centuries, with composers like Chopin, Tchaikovsky, Delibes, Strauss, and others, but also from their avatars since the 17^th century, like works from Lully and Rameau, for example, and with the minuets from the 18^th century.