Mario Zeffiri has an excellent international reputation as a leading interpreter of the bel canto repertoire and has performed as a guest artist in principal theaters throughout Europe, especially in Italy (including Teatro alla Scala, Opera di Roma, Teatro Regio di Torino, Teatro Comunale di Bologna, Teatro Comunale di Firenze, Teatro Verdi di Trieste, Teatro Filarmonico di Verona, Teatro La Fenice, and Teatro San Carlo di Napoli). Outside Italy, he has performed at Opéra National de Paris, Théâtre des Champs-Elysées, Opéra Comique de Paris, Opernhaus Zurich, Gran Teatre de Liceu Barcelona, Deutsche Oper Berlin, the Théâtre de la Monnaie in Brussels, as well as in the opera houses of Athens, Bordeaux, Dresden, Düsseldorf, Essen, Frankfurt, Hamburg, Helsinki, Köln, Leipzig, Liège, Montpellier, Nice, Tel Aviv, Santiago, Stockholm, Tallinn, Moscow and St. Petersburg.