Health workers said they were "thrilled" to meet Charles, who is known as the Duke of Rothesay while in Scotland.
During his visit on Friday afternoon, Charles thanked staff for their “dedication and hard work throughout the Covid-19 pandemic”, according to NHS Highland.
Professor Boyd Robertson, chairman of the health board, said: “We were delighted to welcome His Royal Highness The Duke of Rothesay to Caithness General Hospital.
“His Royal Highness spent time chatting with our staff to thank them for their efforts over the last few months and heard their experiences of working across a variety of health and social care roles during the Covid-19 pandemic.
“All of the staff that met him were delighted and it has given the entire team a morale boost after such a demanding and challenging period.
“I would like to thank His Royal Highness most sincerely for his visit to Caithness General Hospital.”