The Centre for Health Protection (CHP) on Wednesday said it was investigating a local case of the mpox virus.
The 43-year-old patient went to a clinic in Wan Chai last week after developing a skin rash.
The CHP said he had earlier visited Thailand and Taiwan and had high-risk exposures during his stay there.
The man is in stable condition at Princess Margaret Hospital.
"An initial investigation revealed that no epidemiological linkages between this case and other confirmed cases recorded in Hong Kong earlier have been found so far," the CHP said in a statement.
People in vulnerable groups are being urged to get vaccinated and avoid close contact with people or animals suspected of infection.