Western Australia's health minister says the state is suffering its most severe flu season on record with 15 deaths and 5777 infections so far this year.

Western Australia is experiencing its most severe flu season on record with 15 deaths and almost 6000 infections so far this year.

The Health Department says 5777 cases have been reported for the year to date, compared with 1293 for the same period last year.

According to the department's latest winter respiratory illness and influenza data report released on Tuesday, 791 people have been hospitalised for the year to date, compared to 268 for the same period last year.

Health Minister Roger Cook told reporters this year's flu season was unprecedented.

"We are suffering from the most severe flu season on record in WA so all our emergency departments are under a lot of pressure," he said on Monday.

"The flu season, which is unprecedented, puts our emergency departments under particular pressure at the moment but I'm proud of how they've responded."

But the Health Department says the flu season began about two months early and it was too soon to know whether it might also end early, which would put it on par with previous seasons in terms of overall severity.