Prince Philip walked into the hospital unaided after traveling there from the queen's Sandringham estate, were he has spent much of his time since retirement.
Prince Philip left Sandringham, located about 100 miles north of London, just as the queen arrived there for her Christmas break following the performance of her duties of opening Parliament Thursday. He's expected to remain in the hospital for several days, raising the possibility he may not be able to spend Christmas with the royal family.
Officials did not indicate whether he will undergo any surgical procedure.
Prince Philip has been hospitalized several times in recent years, for chest pains in 2011 and infections in 2012 and 2017. He underwent hip replacement surgery in 2018.
Queen Elizabeth and Prince Philip have been married for more than 70 years.