Ronaldo was named in the Real Madrid squad for Saturday's home league match against Espanyol after a month out with a calf strain.
Spain defender Michel Salgado was also included in the squad after three weeks out with a similar injury as was England captain David Beckham, who suffered a minor scare on Thursday when he went over on his right ankle after a challenge from Roberto Carlos.
Ronaldo last played in Real's 0-0 draw against Villarreal on January. 8. He limped off after 33 minutes when he suffered a recurrence of a calf injury.
He has had a difficult season with Real, missing all six of their Champions League matches because of injury and suspension, and struggling for fitness after ligament damage to his ankle.
Centre backs Sergio Ramos and Franciso Pavon have been rested while Jonathan Woodgate has retained his place in the squad after returning to action in last week's 2-1 victory at Celta Vigo.
Real are third in the Primera Liga, 13 points adrift of leaders Barcelona. Espanyol are in 13th spot, six points above the relegation zone.