The Duke of Edinburgh went for treatment at the King Edward VII hospital in London as a "precautionary measure" and will remain there for a few days.
It means that the 90-year-old will miss the rest of the Diamond Jubilee celebrations, including tonight's concert at Buckingham Palace.
Buckingham Palace said in a statement: "He is understandably disappointed at missing tonight's Jubilee Concert and tomorrow's engagements."
His condition is not said to be linked to Sunday's Thames River Pageant, where he stood for four hours in cold and wet conditions.
The Duke will now also be absent for the national service of thanksgiving at St Paul's Cathedral tomorrow (Tuesday), as well as the carriage procession from Westminster Hall to Buckingham Palace, and the balcony appearance.
The Diamond Jubilee concert will be attended by 12,000 people and feature stars such as Sir Paul McCartney, Dame Shirley Bassey, Stevie Wonder, Kylie Minogue, Jessie J, Robbie Williams, Ed Sheeran and Cheryl Cole.
The prince underwent treatment for a blocked coronary artery in December 2011, spending Christmas in hospital as he recovered from the "minimally invasive procedure of coronary stenting".