Prince Philip is responding well to treatment.
The Duke of Edinburgh was taken to Aberdeen Royal Infirmary on Wednesday (15.08.12) as a "precautionary measure" after suffering from a recurrence of a bladder infection and although he is expected to stay in hospital for a few more days, he is doing well.
However, Buckingham Palace said the 91-year-old prince still needs to rest.
The duke is in touch with his family by phone but no visitors are expected today.
In June, Philip was taken ill after spending hours on a ceremonial barge in rain and a cold wind as part of a flotilla of 1,000 vessels on the River Thames to mark the queen's landmark Diamond Jubilee.
Royal aides said he was treated with antibiotics and made good progress before being released six days later.
In December he had a heart operation where surgeons cleared a blocked coronary artery and inserted a stent to ease the problem.
Since then, Queen Elizabeth has tried to get him to slow down.
Queen Elizabeth's cousin Margaret Rhodes said: "It was horribly worrying for the queen when he had that little heart scare at Christmas. She was trying to make life easier for him, but he doesn't like that. He wants to be able to carry on in his old ways, which is wonderful, at his age. You go on doing something you've always done until for some reason you can't do it any more."