High-profile Sydney brain surgeon Charlie Teo is facing a five-day disciplinary hearing before the Health Care Complaints Commission, after allegations of operating without medical oversight.

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

The doctor was swamped by a large media contingent when he arrived for the hearing in central Sydney on Monday.

"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."

Some prominent supporters who turned out to support the embattled surgeon include cricketing legend Steve Waugh and former rugby league star turned boxer Anthony Mundine.

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.

News coverage has revealed numerous other complaints about the surgeon, including claims he charged exorbitant fees.

Dr Teo has consistently denied any wrongdoing.

He said he hoped for a "fair hearing" and that "due process" will be followed.

"I'm really sorry to all those patients suffering from brain cancer and brain tumours," he told reporters.

"The truth lies between what you've heard and what I'm going to say."