Yael Cass emailed staff in early January advising that she would not continue in her role at the end of a five-year term that has polarised the transplant community and seen the OTA become the object of intense scrutiny by government, doctors and donation advocates.

She walked out of the building a week before the release of statistics on Wednesday that showed a record number of organs were donated in 2015 and the authority had exceeded the government target of 18.2 donors per million of the population, with a rate of 18.3.

This corresponded to 1241 organ recipients in 2015, a 55 per cent increase since the authority was formed in 2009, and 435 organ donors - a 76 per cent increase.

The private advocacy group ShareLife has criticised the authority for failing to improve the rate of organ donation in Australia, which lags behind other Western countries, and the government commissioned a review of the OTA's performance following lobbying from the group last year.

That prompted Channel Seven Sunrise host David Koch to quit on live television as the chairman of the OTA, accusing the government of caving in to "the tripe dished out by a whole lot of rich lobbyists" in ordering the review, which would become the second in the authority's short history.

The $212,000 Ernst and Young review was released by the government last week, finding that the strategy to improve the organ donation rate was "sound" but there was room for improvement.

It recommended a new board of governance to mentor the chief executive and support the OTA, which might help foster a culture of debate and mitigate a culture of "defensiveness" by the authority.

Ms Cass is known for her formidable intellect and was respected in medical circles, but less among consumer groups, which complained she lacked sensitivity and was not consultative.

Ann Cahill-Lambert, who served until 2013 as the consumer representative on the OTA advisory council, said the organisation was not transparent with its data and books and did not engage in genuine consultation.

"But trying to bring eight jurisdictions under one umbrella is quite difficult because there are so many players in the system - physicians, surgeons, nephrologists, community groups - and they're all 'my way or the highway'," Ms Cahill-Lambert said.

"It's difficult to bring those disparate groups together and I think the authority has been successful up to a point."

Many transplant surgeons were dismayed by the departure of Ms Cass, who had privately indicated she wanted to see through the work of improving organ donation rates at the OTA.

Surgeon Henry Pleass, who describes himself as "neutral" in transplant politics, said Ms Cass had turned around organ donation in Australia.

"I was very sad to hear she was leaving and that was shared by the transplant community," Dr Pleass said.

"All the negative feedback has been very unfounded. Things don't happen overnight - you've got to have a whole cultural change.

"2014 was a bit of a disappointment but 2013 was the highest previous peak and we've beaten that by a significant amount."

ShareLife director Brian Myerson said he was pleased that the acting chief executive of the OTA would be health official Felicity McNeill, who helped broker the government's agreement with the Pharmacy Guild of Australia last year.

"It appears she really is a change agent and that's exactly what we need," Mr Myerson said.

He also welcomed the latest figures on organ donation, though he warned they could be a one-off.

"We're hoping things are getting in place, but we'd really need to look at the reasons for the increase."

The minister responsible for organ donation, Fiona Nash, said a new chief executive would be appointed by the new board of governors.

"Yael Cass's five-year term as CEO of the Organ and Tissue Authority expired on February 4, 2016," Ms Nash said.

"The government sincerely thanks Ms Cass for her years of determined and tireless service to the cause of saving lives through organ donation and transplantation.

"After Ms Cass's five years as CEO of the Organ and Tissue Authority, it makes sense to allow applicants from around the globe to apply for this important position."

Ms Cass declined to comment.