Opposition health spokeswoman Helen Shardey said Metropolitan Ambulance Service figures obtained under freedom of information showed 46 per cent of patients had to wait more than 15 minutes.

Between January 1 and July 31, the emergency department had to cope with the most ambulance arrivals of any Victorian hospital (10,047), but also had the highest rate of patients waiting 15 minute or more. Statewide, about 29 per cent of ambulance patients waited longer than 15 minutes.

Ms Shardey said ambulance patients endured long waits because of the State Government's failure to adequately fund hospitals.

"Patients are not only waiting for hours once they enter the emergency department, but now patients are waiting hours before they even go through the doors."

A spokesman for Health Minister Daniel Andrews said this year was "probably the busiest on record for Victorian hospitals".

"I am proud to say the system has coped, patient safety has not been compromised and Victorians continue to get the best of care from our skilled and dedicated staff."

He said all "credible sources", including the Federal Government and Australian Medical Association, rated Victoria's emergency departments as the best in Australia.

Monash Medical Centre failed to respond before deadline.