The Duke of Edinburgh was absent from Sunday's Easter service at Windsor Castle, which was attended by the Queen.
Philip, who has effectively retired from royal duties, did not attend the Easter Mattins Service at St George's Chapel - where Prince Harry will marry Meghan Markle in May.
The church service is the latest event the 96-year-old has missed in recent days and it is understood he has been experiencing some trouble with his hip. It is not thought to be a serious issue as he was spotted driving in Windsor Great Park on Wednesday.
The Duke and Duchess of Cambridge arrived late for the service - turning up after the Queen had already gone in.
William and Kate were the last royals to arrive - driven down the hill to St George's Chapel at Windsor Castle in a car - and going in a few minutes after the scheduled 10.45am start time.
Kensington Palace declined to comment when asked about the couple's late arrival.
The Duchess, who is expected to give birth to her third child this month, is now on maternity leave.
Harry and Meghan were not at the service, with Kensington Palace describing their weekend plans as "private".
The Duke of Edinburgh stepped down from his public duties last summer, but on occasion does attend events with the Queen.
When it was announced last year that he would be retiring from official engagements, Buckingham Palace stressed that the decision was not health-related and he had the full support of the Queen.
Members of the public waited outside the chapel as the 91-year-old monarch arrived.
Prince Andrew and his daughters Princess Beatrice and Princess Eugenie attended the Easter service, along with Eugenie's fiance Jack Brooksbank.
The Princess Royal and her husband Vice Admiral Sir Timothy Laurence led the royal family down the hill to the chapel, and were joined by Zara Tindall.
Princess Anne's son Peter Phillips and his wife Autumn, Prince Edward, the Countess of Wessex and their children Lady Louise Windsor and James, Viscount Severn, also attended the service.