The former Madrid director has voiced his concerns with the Spain goalkeeper's lack of gametime ahead of the Champions League final
Casillas has solely been used in cup competitions by head coach Carlo Ancelotti this campaign, with Diego Lopez starting every Madrid fixture in La Liga.
However, Valdano, who left the Bernabeu in May 2011. believes the time has come to reinstate the 32-year-old as Madrid's first choice goalkeeper.
"Casillas not playing until the final is a problem," he told Cadena Ser.
"I would give him minutes. It's a long time without playing."
If Ancelotti persists with his current selection process, Casillas will not feature again until the showpiece in Lisbon on May 24 - some 25 days after Madrid's semi-final victory over Bayern Munich.