The Duke of Edinburgh is responding well to treatment for a bladder infection.
The Queen's husband was taken to Aberdeen Royal Infirmary on Wednesday evening.
Doctors have said that the 91-year-old still needs more rest so will be staying in hospital for a few more days so they can watch his condition.
He'd been with the Queen at her home in nearby Balmoral Castle.
It's the same infection that led to him needing five nights in hospital in June, after the Diamond Jubilee Pageant on the River Thames.