Prince William and Prince Harry, plus Prince Charles and the Duchess of Cornwall, are visiting the Duke of Edinburgh in hospital in London.
Prince Philip underwent exploratory abdominal surgery last Friday.
The Queen visited Prince Philip in hospital as the Palace described him as "comfortable and in good spirits" following an operation.
The Duke of Edinburgh will celebrate his 92nd birthday, as he did Christmas in 2011, in hospital.
Buckingham Palace say they expect him to remain there for up to a fortnight, but did not say what the exploratory operation was for.