Ronaldo has been out of action since August with a muscular and knee problem, but was expected to start against Siena next weekend.
"Yesterday morning I received a phone call from chief medic Meersseman, who told me it was probably better for Ronaldo to stay in Brazil for a few days, so I accepted," revealed general manager Adriano Galliani.
"The way players are dealt with at MilanLab has my utmost confidence. I do not think a couple of days in Brazil can make much of a difference or open up any kind of scandal.
"Despite what the newspapers say, I am not at all disappointed or angry. We are very relaxed about the situation."