The WHO said on Friday it expected to announce the removal of the island from what was once a long list of infected regions or countries where new cases of the deadly virus had been reported within the previous 20 days.
The normal incubation period for the disease is 10 days, and twice that time is the mandatory transmission-free period before the WHO can declare a local emergency situation over.
The move, due to be announced at a news conference called for 0700 GMT, will close the current list of local transmission of the potentially fatal Severe Acute Respiratory Syndrome (SARS), which has killed some 800 people worldwide.
At one time several Chinese provinces and the capital Beijing, Hong Kong, Toronto, Singapore, Vietnam's capital Hanoi, and the Philippine capital Manila were on WHO SARS lists.
Authorities in Taiwan, where nearly 700 cases and 84 deaths over the past three months curbed travel and dealt a blow to the economy, are expected to give a warm welcome to the decision.
But with some 200 people worldwide still in quarantine and a good chance that some cases may have slipped through the net, it is too soon to claim SARS has been beaten, health experts say.
"It will be by no means a declaration that the world is SARS-free," said one.
Nevertheless, health officials say the event will be an important milestone in the fight against the disease, which emerged in southern China last November.
The WHO's top officials -- Director-General Gro Harlem Brundtland and David Heymann, Executive Director of Communicable Diseases -- are due to make the announcement, underlining how important they feel it is.
The previously unknown disease, which is linked to the corona family of viruses which cause the common cold, quickly spread to 30 countries, helped by global travel, and prompted the WHO to issue a global alert in March.
Its virulence startled the health community which is still trying to establish its origin and how it is spread.
The fact that it jumps from one infected person to another easily, even in well-equipped modern hospitals where many victims have been doctors and nurses, means countries will have to be on guard for some time to come, the WHO has warned.
Officials in Toronto, the Canadian business capital taken off the local transmission list on Wednesday, say they will stay vigilant for SARS, for which there is no simple treatment.
"We're not out of the woods yet. It is likely we are going to have to deal with this disease for some time," a spokesman for Ontario's Health Ministry said.