Prince Philip has undergone a "successful" hip operation and is recovering well, Buckingham Palace has announced.
The 96-year-old husband of Britain's Queen Elizabeth II was admitted to London's King Edward VII Hospital on Tuesday for the planned surgery. He is likely to remain there for several days, the palace said.
"He is progressing satisfactorily at this early stage," a palace statement said, adding that the Duke of Edinburgh is "comfortable and in good spirits."
For is age, the Duke is in good health. In 2016, he represented the royal family at 200 engagements.
In June 2017, he spent two nights in hospital as a "precautionary measure" for the treatment of an undisclosed infection.
On Sunday, he was absent from the Easter service attended by the Queen and other members of the royal family at St. George's Chapel in Windsor -- also the venue for Prince Harry and Meghan Markle's wedding on May 19.
Prince Philip retired from 65 years of public service in August 2017, more than five years after the palace first said he would gradually "wind down" his workload, though he remained keen to carry out many of his duties.
Queen Elizabeth, 91, has also begun to scale back her duties due to her advancing age, handing over some of her responsibilities to her eldest son and heir, Prince Charles.
The Queen and Prince Philip celebrated their 70th wedding anniversary last November. The Duke is the longest-serving consort of a reigning British monarch.