Dr Charlie Teo has turned up to a medical hearing supported by a number of high-profile sports stars, including boxing great Anthony Mundine, after allegations of operating without medical oversight.

The controversial neurosurgeon held the hand of his glamorous girlfriend Traci Griffiths, a former patient, as he arrived at the inquiry in Sydney on Monday.

Dr Teo is facing a five-day-long Health Care Complaints Commission (HCCC) hearing over allegations of unprofessional behaviour during some of his operations.

In August 2021, the controversial neurosurgeon was restrained from operating without another doctor's approval by the NSW Medical Council after an investigation by the HCCC.

Protesters gathered outside the building and held up signs defending Dr Teo, with Mundine and former cricketer Gavin Robertson showing up as well.

Former Australian cricket captain Steve Waugh and his wife Lynette were also in attendance with the cricket legend a former patient of Dr Teo.

Waugh had a large blood clot removed from his brain in 2006 and is considered to be a long-time friend of Dr Teo.

'I've referred him to a number of friends as well,' Waugh said.

'He's done an amazing job – over 11,000 operations. He takes some of the tough cases no one else wants to'.

Mundine said it was a 'ride or die' situation for Dr Teo as he fought the allegations.

'This has taken a toll on him,' he said. 'But look how many people are here for him, he is obviously a lifesaver who is well-respected.'

Mundine also addressed the criticism heaped onto the neurosurgeon. 

'There will be people that hate it … it's a 50/50 game, you're gonna win some, you lose some,' he told Newscorp.

'But I'm here. If you want to kick him, come kick me too.' 

The neurosurgeon denied any wrongdoing as he was swamped by media outside the steps of the NSW Medical Council.

'It's been a long road. It's sad that we're in this situation,' he said.

'I'd much rather be operating on Monday than doing this.

'I'm really sorry to all those patients suffering from brain cancer and brain tumours. The truth lies between what you've heard and what I'm going to say.'

Former patient Tammy Thompson was among the supporters who had been operated on by the surgeon in 2018.

'Without him I wouldn't be here, it's upsetting to see him treated this way and that's why I'm here,' she said. 

Holding a placard with the text 'In Teo, I trust and believe,' Ms Thompson said she took a day off work and flew from central NSW to show that her surgery was a success.

'I trust Teo because at no point did he sugar-coat anything. He was straight down the line,' the 50-year-old told AAP.

'I was back at work six weeks after my operation ... I'm one of those success stories and I'm upset for those (who) haven't had the success, but what isn't a risk in life?'

Another supporter Alan Suey says Dr Teo saved his eight-year-old daughter's life in 2020 when he operated on her diffuse intrinsic pontine glioma - a type of aggressive brain tumour.

'We knew all the risks but we decided to go ahead with the surgery,' he told AAP.

'I know he's a genuine guy and he's done so much good. At the end day he saves lives - there are some bad outcomes and it's unfortunate.'

The show of support from the close friends of Dr Teo comes after the neurosurgeon sent texts and emails to his acquaintances asking them to show up and support him. 

Dozens showed up in support with only 17 seats designated to members of the public in the hearing. 

He hugged his daughter Sophie before heading into the NSW Medical Council building. 

Dr Teo is famous for performing neurosurgery on cancer patients with tumours other doctors have deemed 'inoperable'. 

He has been banned from operating unless a second doctor is satisfied his patients are aware of the risks and are financially informed about their decision. 

The ban comes following a previous investigation into alleged unsatisfactory conduct in the workplace.

The first witness to speak at the hearing described his wife's diagnosis of stage 4 glioblastoma - an aggressive brain tumour.

The witness, who can't be identified, said the tumour was found in 2018, and he and his wife were told by a different neurosurgeon surgery would offer no benefit.

'We were grabbing onto any hope we could,' the man said, revealing he and his wife had heard about some of Dr Teo's positive cases.

He said his neurosurgeon refused to write a letter of referral for Dr Teo.

It's unclear yet what the result of Dr Teo's treatment was of the man's wife, but he said he could potentially give her 12 more years - more than the 12 months she was initially told she would have left to live.

Dr Teo informed them the operation had a 5 per cent risk of death and 50 per cent risk of minor complications.

Dr Teo, who can also no longer work in the USA or Singapore, says he has been demonised in the Australian press - and he insists it's costing lives.

'I don't know why a particular journalist or particular newspaper, a particular show or 14 particular neurosurgeons have taken on this task of destroying me,' Mr Teo, 64, told Wizard Home Loans founder Mark Bouris on his Straight Talk podcast.

'But as long as they understand they have blood on their hands.

'I really want them to know that. I want them to know that, you might not like me, you might want to destroy me, and you've succeeded.

'But there's not a day goes by that I don't see a case that's died, or was going to die that I could have saved. It's terrible.'

Dr Teo says his ground-breaking brain surgery on 'inoperable' tumours was at first lauded by patients and the media, and gave him a 'Bambi-like' reputation.

But he argues his Messiah-like status was sabotaged by jealous rivals and the media.

'I don't know who's behind it all but all the media has basically tried to make me look like I'm some sort of terrible person,' he said.

'Once they came out with all those headlines, all the colleagues who were jealous and fuming, wanting to destroy me, go, 'Yes, Now we can go in for the kill!'

'It was like a wolfpack seeing blood - a feeding frenzy. All these complaints started coming in.

'Suddenly, Bambi was no longer Bambi. Bambi was a demon. And now we can go get him and we destroy him.'