The purchase will dent the Portuguese captain’s deep pocket by as much as £35.5million, according to reports.
Plenty of Greek Islands are now for sale following the economic meltdown in the country.
Portuguese outlet Move Noticias says Ronaldo has splashed out on one of the islands.
Ronaldo has been given time away from Madrid training to attend Mendes’ wedding to Sandra, which will take place in Portugal. Ronaldo is Mendes best man.