Renato Macario was on the Italian national rowing team in the early years after World War II. The highlight of his international career took place at the 1947 European Championships held in Lucerne when his coxed fours lost the gold medal by just 6/10ths of a second, beaten by a French crew. The following year, at the London Olympics, Macario rowed with the same coxed four, all the athletes from Società Canottieri Sebino, but they failed to reach the final, being beaten in the semi-finals by the eventual silver medalist, Switzerland.