Abstract The Teatro di San Carlo (Naples—Italy) is known to be the oldest working theatre in Europe. Since its opening on 4 November 1737 (41 years before the opening of La Scala in Milan and 51 years before the opening of La Fenice in Venice) a number of famous singers, musicians, conductors, and other artists as well, have brought great prestige to this theatre. The San Carlo is not short of praise for its acoustics but, to the knowledge of the authors, no objective study about this subject has ever been published. This paper reports the results of acoustic measurements carried out with the aim of obtaining objective parameters describing the acoustics of the San Carlo from the point of view of the listeners. They disclose a behaviour of the theatre that is typical of the Italian style opera house