Ambulance ramping outside busy Perth hospitals soared 142 per cent in the September quarter compared with the same time last year.
The latest Health Department report card shows ambulances were forced to wait to hand over patients to emergency departments for 4581 hours in the September quarter compared with 1891 hours in 2011.
Shadow health minister Roger Cook said the State Government was failing to meet its promise of reducing pressure in emergency departments.
"The solutions that (Health Minister) Kim Hames lauded in May that would fix the problems have clearly not done that," Mr Cook said.
"He talks about how well things are going in emergency departments when many patients can't get into those departments because they're stuck in ambulances, so the Government had just shifted the problem elsewhere."
Dr Hames said the ambulance service was performing well after a difficult winter because of the flu.
He blamed Labor for bed shortages, saying it had delayed key aspects of hospital reforms it instigated while in government.