The São Carlos Opera House Chorus was formed in 1943 under the direction of Mario Pellegrini performing on a permanent basis in the great operatic repertoire as well as in sacred music. Between 1962 and 1975 the TNSC Chorus participated in the Companhia de Ópera Portuguesa Season ( Portuguese Opera Company, then based at Teatro da Trindade) and toured to Madeira, Azores, Angola and, 1965, to Oviedo by invitation of Teatro Campoamor. It was awarded the Classical Music Award by Casa da Imprensa (The Press House). The choir took part in world premieres of operas by Portuguese composers such as Fernando Lopes Graça's D. Duardos e Flérida (1970) and António Victorino d’Almeida's Canto da Ocidental Praia (19721). The first full-time choral nucleus was formed in 1980, whilst the Chorus' professional status was achieved in 1983 under the direction of Antonio Brainovitch.
Gianni Beltrami, who assumed its leadership in 1985, is responsible for the Chorus’ total artistic affirmation benefiting from working conditions till then unheard in Portugal. The following works marked that phase: Stravinky’s Oedipus Rex, Kurt Weil’s Rise and Fall of the City of Mahagonny, De Pablo’s Kiú, Ravel’s L’Enfant et les Sortilèges and Purcell’s Dido and Aeneas. At the invitation of RAI, the chorus participated in Berlioz’s Grande Messe des Morts in Turin. After Gianni Beltrami’s death, João Paulo Santos took on the direction as the first Portuguese to hold that position in the entire history of the São Carlos Opera House. He was responsible for successes such as Boito’s Mefistofele , Corghi’s Blimunda and Divara, Mahler’s Symphony No. 2 with the European Community Youth Orchestra, Haydn’s Die Schöpfung, Schnittke’s Faust and Requiem, Stravinsky’s Perséphone and Le Rossignol, Tchakovski’s Evgeni Onegin, Berlioz’s Les Troyens, Janácek’s Glagolitic Mass, Wagner’s Tannhäuser and Die Meistersinger von Nürnberg and Ligeti’s Le Grand Macabre. In 1991, Europália Celebrations took the Chorus to Brussels to perform in Verdi’s Requiem. (1991).
Within the scope of Expo-98, the Chorus performed at the closing concert and has sang under the direction of some of the most prestigious maestri such as Antonino Votto, Tullio Serafin, Vittorio Gui, Carlo Maria Giulini, Oliviero de Fabritiis, Otto Klemperer, Molinari-Pradelli, Franco Ghione, Alberto Erede, Alberto Zedda, Georg Solti, Nello Santi, Nicola Rescigno, Bruno Bartoletti, Heinrich Hollreiser, Richard Bonynge, García Navarro, Wolfgang Rennert, Rafael Frühbeck de Burgos, Franco Ferraris, James Conlon, Harry Christophers, Michel Plasson and Marc Minkowski, among others. The TNSC Chorus was awarded the Classical Music Award by Casa da Imprensa (The Press House) and has also participated in operas and concerts conducted by the most important Portuguese conductors, Pedro de Freitas Branco being of special note. Maestro Andreoli is its present Chorus Master.