The Portugal captain has not featured since Real's UEFA Champions League quarter-final first leg victory over Borussia Dortmund on April 2 due a knee injury and then a thigh problem.
But the FIFA Ballon d'Or winner appears to be on course to play in Wednesday's semi-final first leg of Europe's premier club competition against Bayern Munich at the Bernabeu, while Sergio Ramos - recently troubled by a neck injury - also trained on Sunday.
There was more positive news for Real coach Carlo Ancelotti with the sight of Marcelo training following a lay-off with a hamstring injury.
Real revealed on their official website: "Cristiano Ronaldo and Sergio Ramos were both in the Cuidad Real Madrid on what was otherwise a day of rest for Carlo Ancelotti's squad ahead of the first leg tie with the German outfit in the semi-finals of the Champions League.
"Also in attendance at the training session were Marcelo and Casemiro. The Portuguese trained intensely on his own, with and without the ball.
"Meanwhile, Sergio Ramos and Casemiro worked on their physical fitness. The defender also did some ball work. Marcelo also trained on the grass, while Pepe and (Alvaro) Arbeloa used the indoor facilities to exercise."
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