Perth drinkers out for a night on the town have twice the blood alcohol levels of those in Sydney and are among the nation's biggest pre-loaders, a major study has found.

Surveys and breathalyser testing of 6500 people in popular nightspots in Perth, Melbourne, Sydney, Geelong and Wollongong found Perth and Melbourne drinkers had the most extreme levels of intoxication at 4am, with an average blood alcohol content of 0.11.

The results, released by the National Drug Law Enforcement Research Fund, come from one of the biggest studies into the behaviour of Australians on a night out.

Of 1200 randomly picked people tested between 10pm and 5am in central Perth and Northbridge early last year, the average blood alcohol content was 0.066, double that of Sydneysiders, who recorded an average of 0.033.

The average reading among Melburnians was 0.048, while Geelong drinkers had the highest at 0.067.

Perth drinkers reported high levels of pre-loading, with 80 per cent having an average of six drinks before going out, compared with 65 per cent of drinkers nationally having an average five drinks.

Apart from asking people how much they drank and how intoxicated they felt, researchers took drug swabs and breath-tested patrons at hotels, nightclubs and bars as well as those at fast-food outlets or waiting for a taxi.

They also carried out "covert observations" by recording signs of people being drunk such as slurred speech, spilling drinks and glassy eyes, and noting levels of violence, abuse and sexual misbehaviour, including five incidents in Perth.

Associate Professor Peter Miller, from Victoria's Deakin University, said the findings showed many people out for a night were drunk. Many were intoxicated before they got there because they pre-loaded at home, with Perth and Geelong people the worst offenders. He said almost 30 per cent of those tested had a blood alcohol content of more than 0.1 - double the legal driving limit - and the highest averages were in Perth and Geelong.

"Make no mistake, that's drunk, visibly drunk, yet it's also clear from the rising alcohol levels later in the night that many continued to be served alcohol when they shouldn't have," he said.

"We have to change the culture, and we need a strong educational campaign to do that, not just a short advertisement on television on a Sunday afternoon that blames parents."

McCusker Centre for Action on Alcohol and Youth director Mike Daube said the results were timely, given the current review of WA's Liquor Control Act.

"If anybody thought that we didn't have a night-time alcohol problem, this report makes scary reading because it's binge drinking at its worst," he said.

"Worryingly, there are aspects where Perth does worse than the rest of the country. We don't need to become the pre-loading capital of Australia."

Professor Daube will write to all relevant State Government ministers asking them to set up a ministerial committee to address issues around late night intoxication, including pre-loading and the promotion of energy drinks.