Cajo Mario is an opera seria in 3 acts by composer Niccolò Jommelli.
The opera's Italian language libretto by Gaetano Roccaforte is based on Lucius Anneus Florus's Tito Livio e Plutarco.
All of the parts are written for castrati, except for the title role, written for a Tenor.
The work premiered on 6 February 1746 at the Teatro Argentina in Rome.
[1] This article about an Italian-language opera is a stub.