The Duke of Edinburgh is in hospital with bladder infection, report sources.
The 91-year-old Prince Philip was driven by ambulance to Aberdeen Royal Infirmary while staying at Balmoral with the Queen, BBC quoted a Buckingham Palace spokesperson as saying.
He is not thought to be in a critical condition, the report added.
This is for the third time in last nine months that Prince Philip has to visit hospital. On Christmas, he had to spend four days in hospital, following an operation to clear a blocked heart artery.
He was last seen at public engagements in the seaport town of Cowes earlier this week