It is thought the men contracted the bacterial lung infection by contaminated water, vapour or dust in the Town Hall area of the CBD.
NSW Health is asking anyone who has been in the Town Hall area who experiences symptoms of the disease to go to their GP.
Symptoms include fever, chills, a cough and shortness of breath, NSW Health’s director of communicable diseases, Dr Vicky Sheppeard, said.
The department has begun inspections of cooling towers in the CBD.
Published by: ABC News, 9/3/2016