By 1955, after beating a variety of top fighters such as Paddy DeMarco and Kenny Lane, Dupas was the top-ranked lightweight in the world.
He defeated future middleweight champion Joey Giardello in 1961, but lost a 1962 welterweight title shot to Emile Griffith.
Lineal Light Middleweight Champion Denny Moyer came to New Orleans on April 29, 1963, and Dupas won the title with a fifteen-round unanimous decision.
[4] He lost the title in September of that year to Italian Sandro Mazzinghi by a thirteen-round knockout.
His brother Tony, also a former fighter, moved Ralph from Las Vegas back to New Orleans and put him in a nursing home.