A new study says eight per cent of professional sports fans who agreed to be surveyed were legally drunk when leaving the stadium after a game.

The study, published online in the journal Alcoholism: Clinical & Experimental Research, found about 60 per cent of fans surveyed had blew a zero on a breathalyzer, 40 per cent tested positive for alcohol in their blood. In total, 8.4 per cent were legally drunk, with a blood alcohol level higher than .08.

However, the lead author of the study admits the sample size was small, as few fans wanted to blow on a breathalyzer after the game.

"Getting fans to submit to a breath test and participate in a brief survey following a football or baseball game is not an easy task," Darin Erickson of the University of Minnesota said in a statement.

"We conducted BAC tests of 362 adult attendees following 13 baseball games and three football games. This is a preliminary study, but the first one to actually attempt to measure BAC levels after professional sporting events in the U.S."

However, Erickson says even with the small sample it suggests that 5,000 fans could be leaving a football game legally drunk.

"That's a lot of drunken individuals who could be involved in traffic crashes, assaults, vandalism, crime and other injuries," Erickson said.

The study found that tailgaters were 14 times more likely to be drunk after the game than their non-tailgating counterparts.

The study was funded by the Substance Abuse Policy Research Program of the Robert Wood Johnson Foundation.

A 1992 Canadian study had similar results.