Dr Kieran McCarthy, who did multiple deployments as a military doctor, told the Royal Commission into Defence and Veteran Suicide that he set up his specialised GO2 practice because after being in the military "the general public annoy me".

He said demand for their services was now so overwhelming he had an eight to nine week waiting list, while his fellow doctors and allied health staff were getting "smashed" and at high risk of burn out.

"The doctors literally can't cope and just leave because it's just too hard ... It's very difficult to attract people into this space," Dr McCarthy said.

He said his Brisbane practice was largely focused on providing comprehensive care for veterans transitioning back into civilian life.

"We have been shocked by the level of physical and psychological injury with the veterans, the sheer numbers of people seeking our help," he said.

After working with special forces in Afghanistan he said he had been well prepared for his return to civilian life.

But most of the veterans he saw had been involuntarily discharged due to injury, and "they are not ready for it, they don't want to do it ... they just fall in a heap".

"We offer long consults. We need time to look after these people, they are highly complex, some of the most complex humans I have ever met in many ways," he said.

There were also major financial challenges for the practice, including a high level of no shows by veterans - around 16 per cent - when they were booked for specialist appointments like physiotherapists.

That meant the Department of Veterans Affairs, which already paid notoriously low fees, would refuse to reimburse the practice for the costs.

Dr McCarthy said if he tried to send the bill to veterans, they would leave or "we get yelled at".

"They don't know how the real world works," he said.

The commission heard the GO2 practice had been so successful, the DVA wanted them set up next to every barracks in Australia.

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Australian Associated Press