Charles was due to visit two farms in North Yorkshire this afternoon. The Prince offered his sympathy to farmers around the country.
A spokesman from Clarence House said: "The Prince of Wales is so sorry that the new outbreak of foot-and-mouth disease means that he is unable to visit Grange Farm and Hill Top Farm in the North Yorkshire Moors.
"His heart goes out to farmers everywhere and he hopes and prays that this desperate situation will soon end."
The Prince, who is patron of the Mutton Renaissance Campaign, was also due to officially launch the new mutton season at Grange Farm in Levisham, near Pickering.
After a tour of the farm, Charles was to mark the launch by tasting a dish of mutton stew, freshly prepared by chef Brian Turner. He was then scheduled to meet farmers and business leaders at Hill Top Farm in Spaunton.