Former US first lady Nancy Reagan is said to be recovering slowly after breaking ribs in a fall.
The announcement was made at the Reagan Presidential Library in Simi Valley, California, where Mrs Reagan, 90, was expected to attend a speech by House of Representatives Budget Committee chairman Paul Ryan.
Library executive director John Heubusch said from the stage that the former first lady was unable to attend because of her injury and was watching the event on TV at home.
Mr Heubusch says the fall at Mrs Reagan's Los Angeles home happened about six weeks ago.
Her spokeswoman Joanne Drake said Mrs Reagan had been adding a few appointments to her schedule but was advised by her doctor not to attend large events.