The Portuguese star was nominated to do the viral charity craze by Darren Fletcher, while the Brazil international asked Camilo Zuniga to follow his lead
The craze, which involves dumping a bucket of ice water on your head, is in aid of the ALS Association and a number of celebrities have been videoed doing it.
Ronaldo was nominated by former Manchester United team-mate Darren Fletcher and, in turn, challenged American singers Beyonce, Jennifer Lopez and Lil Wayne to follow suit.
Another football star to have joined the fad was Barcelona Neymar, who was nominated by Brazil team-mate Marcelo.
The 22-year-old, successful did the challenge and posted a video of it to his Instagram account and nominated new Santos signing Robinho and, with a hint of humour, Camilo Zuniga, who injured him when the Selecao faced Colombia in the World Cup earlier this summer.
ALS, also known as motor neurone diswease and Lou Gehrig's disease after the former baseball star whose life it claimed, is a neurodegenerative disease that causes people to lose muscle function.