The deaths of the five brings Indonesia's bird flu death toll to 30.
Four of the people who died lived in northern Sumatra and were from the same family. The WHO has sent a team to the area to investigate.
An Indonesian health ministry official told Reuters news agency there was no evidence of human-to-human transmission in the latest cases of the H5N1 virus.
The H5N1 virus has killed more than 100 people worldwide since 2003. It has also devastated poultry stocks.
The majority of deaths have occurred in Asia, but cases in people and birds have also been recorded in Europe and Africa.
Almost all human infections so far are thought to have been caused by direct contact with sick poultry.
Experts fear the virus could mutate into a form that passes easily between humans, possibly sparking a pandemic.
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News Health Avian flu Bird flu H5N1 Pandemic Influenza Spanish Flu WHO Flu Indonesia
