The man was staying at Curry Village, a popular lodging area, in June, and health officials believe he contracted the disease there. A woman who also stayed in the cabins about 100 feet from him has also become seriously ill.
Humans typically contract hantavirus pulmonary syndrome by breathing in rodent feces or urine. Officials confirm that mouse droppings in the area tested positive for hantavirus.
The man, who was from Alameda County in the San Francisco Bay area, would be the first person to die from the disease contracted in the park, though two others were stricken in a more remote area in 2000 and 2010, officials said.
Early symptoms of hantavirus include fever and muscle aches, chills, headaches, nausea, vomiting, diarrhea, abdominal pain and coughing. Health officials advised anyone with those symptoms to seek medical attention.
No other cases have been reported, but symptoms can show up one to six weeks after exposure. There is no specific treatment for the virus, and about one-third of people who contract it will die. The sick woman, who is from Southern California, was expected to survive.
Starting next week, park officials will begin trapping and testing deer mice in Yosemite Valley.
There have been 60 cases in California and 587 nationally since hantavirus pulmonary syndrome was first identified in 1993. The two new cases bring the number of people stricken in California to four this year.
The Associated Press contributed to this report.