A study of homeless men has found they suffer from a higher rate of post-traumatic stress disorder than soldiers returning from war.
Mission Australia screened 75 men entering one of its programs in Sydney and found one in five suffer from the disorder.
A spokesman for the charity, Martin Thomas, says living on the streets puts homeless men at higher risk of exposure to physical and sexual assaults and other traumatic events.
"Eighty-nine per cent of them said they had witnesses at least one traumatic event, and it varied from being threatened with a weapon or being held captive or seeing someone else seriously hurt or even killed," he said.
Mr Thomas says the rate of PTSD among homeless men is far higher than for others.
"We know the general population for men of post-traumatic stress syndrome's around 4.6 per cent and we also know of studies overseas that have shown combat veterans coming back from service, the incidence of post-traumatic stress is upwards of 17 per cent," he said.
"So we thought this was quite an alarming, surprising finding for us."
He says proper counselling and support, including accommodation, can greatly improve the lives of homeless men and provide significant savings for taxpayers.