The incidence of severe workplace injuries has risen in each of the past two financial years, new data from government agency Worksafe WA has found.
Its annual review reported better results for workplace injuries and diseases in general, but not for severe injuries.
The report also said there were 18 workplace deaths in Western Australia last year.
Agriculture, forestry and fishing accounted for one third of these deaths; this sector was also had higher injury rates than just about any other industry.
Worksafe WA said the incidence of lost-time injuries and diseases was 9.23 per million hours worked in 2011-12.
This is down slightly from 9.39 in 2010-11 and up from the all-time low of 9.06 in 2009-10.
The current figure represents represents a major decline from 2000-01, when the incidence rate was 13.78 per million hours worked.
In contrast, the frequency rate for severe incidents has risen in the two past years, to 2.66 per million hours worked.
This is well above the frequency rate of 2.17 in 2009-10.
The Worksafe data also show that severe incidents account for an increasing proportion of all workplace incidents, from 21.8 per cent of the total in 2007-08 to 28.8 per cent last year.
UnionsWA said the number and rate of very serious work injuries - which result in more than 60 working days lost - was higher at any time in the past five years.
"This is a cost to industry through workers' compensation, but more importantly people are often left with life-long disability and a loss of livelihood," UnionsWA secretary Meredith Hammat said.
"Clearly more needs to be done, by governments, employers and everyone in WA workplaces."
Aquaculture, agriculture, forestry and fishing had the highest frequency rate for lost time injuries, at 18.9 per million hours worked.