Australia's first pill-testing trial at Groovin the Moo (GTM) Canberra has begun, with some festivalgoers saying they are glad the service is available and they plan to visit the stall.

Advocates for pill testing are under a media ban and unable to comment on the trial while it is underway, but the dozens of attendees the ABC approached all said they supported the trial.

"It's definitely necessary in this day and age, because people are gonna take it, they need to know what they're taking is safe, and they then have that decision whether they want to take it or not," one man said.

"It won't make a difference of who's doing it, it just makes a difference of whether people are gonna die off it," said another attendee.

"If I was gonna take a pill, yeah I'd probably test it," another said.

Attendees can have their pills tested, and learn what the drugs contain. ( ABC News: Timothy Goff )

The ABC understands that at times during the day there was a queue for the pill testing area, and that some attendees discarded their drugs after learning what they contained.

Attendees were notified of the trial on Thursday, when GTM organiser Cattleyard Promotions agreed to allow the testing trial on its site.

Festivalgoers could visit a tent to have their pills tested and given information about the substances the pill contained.

An amnesty bin was available if they chose to dispose of the drugs rather than take them.

Police were on site throughout the event but vowed not to target the pill testing tent.

Statistics to reveal impact of trial

Pill testing is implemented in more than 20 countries and ACT Greens Leader Shane Rattenbury said it was proven as a harm-reduction measure.

"It's been operating overseas for many years, and it's proven very successful overseas as a way of reducing harm, minimising the risks and explaining to young people the real risks of taking some of these drugs," he said.

"All of the experts have said that this is a really important way to minimise, harm, accepting the reality that young people are going to experiment, they are going to take drugs."

"They'll never be guaranteed by the staff that taking drugs is safe, what they can be told is what the risks are."

Participants will be anonymous, but data will be collected to determine what impact the trial had.

"There is real opportunities here in terms of education and knowledge gathering, and also information that can be fed back to the police later, which helps them understand the drug trade more generally," he said.

"How many people discard their pills after the conversation is one of the key measures of success that we've seen overseas."