The Real Madrid forward suffered with injury problems over the course of the summer, but he has scored three goals for his club in their opening four games of the season.
The Portuguese face Albania in their first qualifying match for the tournament, and manager Paulo Bento has admitted that he is concerned over Ronaldo's fitness.
"There's a question over his fitness," Marca quotes him as saying. "Regardless of having played regularly, he can't compete."
However, there are call-ups for rumoured Arsenal target William Carvalho and new Sporting Lisbon signing Nani.
Portugal squad in full:
Goalkeepers: Eduardo (Dinamo Zagreb), Anthony Lopes (Lyon), Rui Patricio (Sporting Lisbon)
Defenders: Andre Almeida (Benfica), Vitorino Antunes (Malaga), Fabio Coentrao (Real Madrid), Ricardo Costa (Al-Sailiya), Neto (Zenit St Petersburg), Pepe (Real Madrid), Joao Pereira (Valencia), Reuben Vezo (Valencia)
Midfielders: William Carvalho (Sporting Lisbon), Andre Gomes (Valencia), Raul Meireles (Fenerbahce), Joao Moutinho (Monaco), Adrien Silva (Sporting Lisbon), Pedro Tiba (Braga), Miguel Veloso (Dinamo Kiev)
Forwards: Bruma (Galatasaray), Eder (Braga), Ricardo Horta (Malaga), Ivan Cavaleiro (Deportivo La Coruna), Nani (Sporting Lisbon), Vieirinha (Wolfsburg)
Tag : European Championship