High rates of staff burn-out and lower funding levels than other states are impacting mental health services in NSW and costing those in need.

Doctors, nurses and psychiatrists weighed in on Monday at the second day of hearings at a NSW parliamentary inquiry into the availability and quality of mental health care.

NSW spends the lowest per capita on mental health of all the states and territories, with Queensland and Victoria both investing hundreds of millions more in the field following their own parliamentary inquiries.

Dr Angelo Virgona, Chair of the NSW Branch of the Royal Australian and New Zealand College of Psychiatrists, told the inquiry it will take a "major investment" to change the landscape of mental health care in NSW and provide the services people deserve.

"We're so far behind at the moment, and we really do need to catch up and it's going to take significant investment," he said.

Dr Virgona flagged an "extraordinary shortfall" in workforce numbers, with just 1400 psychiatrists and approximately 600 people training to be psychiatrists in NSW and shortages particularly impacting rural and regional areas.

"I think workforce is the elephant in the room when it comes to mental health," he said.

Registered nurse Victoria Norris said high rates of burn out in the often challenging field are contributing to shortages.

"There is lacking in support for a lot of our frontline clinicians in the very important and very traumatic work that they do," Ms Norris said.

General Practitioner, Dr Tim Senior who specialises in Aboriginal and Torres Strait Islander health said those most in need of mental health care often find it the most difficult to access.

"Mental health conditions aren't just a condition that exists independent of that; it actually takes away people's ability to navigate the system, either through anxiety or through the sheer effort that requires," he said.

Dr Senior suggested a role such as "care coordinator" could assist patients navigate the complex mental health care system.

"I don't think the system will ever not be complex, but I think recognising that it's complex and that there is a burden of care for many patients where they have other coexisting conditions as well (is important)," he said.

Dr Virgona said that for a growing number of patients presenting with trauma, limited availability of evidence-based therapy and high costs of ongoing care are often extremely prohibitive.

"There's only a few sessions of psychological therapy that's funded under the (Medicare Benefits Schedule); and so being able to fork out the $200 plus a session after their 10 (free) sessions is prohibitive for most people suffering these disorders," he said.

Inquiry chair, Greens MLC Dr Amanda Cohn said the committee had heard evidence from those on the receiving end of care, and it was important to now hear from practitioners and organisations who provide it.

"The committee is particularly interested to hear their thoughts on how we can improve mental health services and support services for those seeking assistance, while also supporting those on the front line delivering vital services," Dr Cohn said.