Britain's Prince Philip, the husband of Queen Elizabeth II, "had a good night" in hospital after is heart surgery and family members would visit him on Saturday, Buckingham Palace authorities said.
The 90-year-old had a successful operation on Friday for a blocked coronary artery, after being taken to hospital by helicopter from the queen's Sandringham estate, where the royal family is celebrating Christmas.
"The Duke of Edinburgh had a good night. There will be some members of the family visiting him this morning in hospital," a spokeswoman for the palace told AFP on Saturday.
The spokeswoman did not give further details of his condition or of which royals were expected to visit him.
But in a separate statement overnight, the palace said the prince had been taken to the Papworth cardiothoracic hospital in Cambridge, eastern England, on Friday after suffering chest pains.
Emergency services were called to Sandringham at around 1800 GMT on Friday and Philip was flown by helicopter to the hospital 62 miles (100 kilometres) away, British media reported.
The palace said tests found the blocked coronary artery, adding that it was "treated successfully by the minimally invasive procedure of coronary stenting.
The procedure involves inserting a tube-like device called a stent into the blocked artery to open it up and help restore a healthy blood flow. It is often performed under local anaesthetic.
"Prince Philip will remain in hospital under observation for a short period," the palace said.
Royal sources said the fact that family members were visiting was no indication that he was likely to stay in hospital any longer than expected, with one source saying that they would "obviously" want to see him on Christmas Eve.
Medical experts said many patients leave hospital only a day after having similar treatment.
"It does not require any major anaesthetic, this is all done when you re awake under local anaesthetic," cardiologist John Barton told the BBC.
"The recovery period is very rapid after this. Very often the people are discharged from the hospital within a day or two."
The health scare came as royals were gathering at the 60-acre (24-hectare) estate in Norfolk, where Prince William's wife Catherine is spending her first Christmas as a member of the royal family.
Prince William, who is the grandson of the queen and Prince Philip, and Catherine married in April.
The queen and her husband traditionally spend Christmas Day morning at St Mary Magdalene Church on the royal estate and greet well-wishers on their way to and from the service.
The Boxing Day shoot usually organised by Prince Philip could also be in doubt.
Greek-born Prince Philip -- who has been married to Queen Elizabeth for 64 years and is Britain's longest-serving consort -- is well-known for his tireless spirit as well as his outspoken views.
He joined his wife on an 11-day tour of Australia in October but has recently suffered occasional bouts of poor health and pulled out of a trip to Italy in October nursing a cold.
In 2012 the queen is due to mark her diamond jubilee celebrating 60 years on the British throne, but while other royals are scheduled to tour the globe next year, she and Philip are set to stay in Britain.