Since fever is a key symptom of the potentially deadly illness that spread panic across much of Asia and Canada not long ago, the four women, aged 24 to 73, are being medically monitored.
One of the four patients tested positive for Respiratory Syncytial Virus (RSV) while results of the other tests were still awaited.
All the four were in a stable condition at the Prince of Wales Hospital in the New Territories.
With 297 deaths and nearly 1800 infections, Hong Kong was the second worst affected region when the SARS epidemic broke out early this year.
The epidemic had affected 8000 people and left more than 900 dead in 32 countries.
The alarm over the four patients is the third SARS-alert in Hong Kong in the past one week.
Seven patients of another hospital on Wednesday developed high fever and upper respiratory tract infections, but tests later showed they were suffering from nothing more than a flu.