More than a fifth of injured patients turning up to Auckland hospital emergency departments are affected by alcohol.

The median amount they'd drunk is 6.4 standard drinks.

The figure's revealed in a study of more than 500 emergency patients on three separate occasions in the past year .

They come at the same time Alcohol Healthwatch releases figures showing Auckland has the highest rate of alcohol related harm in the country.

Late night assaults, 75 per cent which are thought to be alcohol-related, are also higher in Auckland than the rest of the country.

Director of Alcohol Healthwatch Rebecca Williams said the government needs to step up.

She said the cheap pricing of alcohol and the aggressive marketing of alcohol are continuing, while local efforts are struggling to make a difference.

"When you reduce accessibility and availability of alcohol, you can reduce alcohol-related harm and address some of the problems in a drinking culture." 

Auckland University senior lecturer in Epidemiology and Bio-statistics, Dr Bridget Kool, said it's disturbing evidence of the harmful effect alcohol is having on our health system and our communities.

Alcohol plays an even greater role in patients turning up with injuries due to a violent encounter.

Almost 70 per cent of those intentionally injured by another person had been drinking in the six hours prior to their injury.