One in five Bali bombing survivors still suffer high levels of distress and many experience disturbing flashbacks, a study has found.
The University of Western Sydney study also found that survivors fared better if they were married or in de facto relationships and felt they had strong family support.
The 2002 Bali bombings killed more than 200 people, including 88 Australians, and injured more than 200, including 66 Australians.
The study found the Australian survivors were in relatively good physical health but had high rates of psychological distress.
All 55 people who participated in the phone survey in late 2010 were part of the NSW Ministry of Health's Bali Recovery Program.
The study, published this week in the Medical Journal of Australia, found 20 per cent of the respondents experienced high levels of distress, twice the rate of the general population.
Lead author Garry Stevens said the "irrational or meaningless nature of violent death" through terrorism could interfere with survivors' need to make sense of a loved one's death, a central process of grieving.
"Deaths involving deliberate violence are associated with higher incidence of depression and prolonged or 'complicated' grief and a slower rate of recovery," the clinical psychologist said in a statement.
Co-author and a senior NSW Ministry of Health psychologist Julie Dunsmore said many respondents reported frequent unwelcome thoughts about the tragedy.
"Half of the group interviewed reported that, in the previous month, they had experienced upsetting thoughts, dreams or 're-experiences' related to the Bali bombing or the need to avoid such thoughts and feelings," she said.
Mr Stevens said the study showed the health and daily functioning of the Bali bombing survivors was generally good, but a significant number continued to experience high levels of distress and trauma linked with complicated grief symptoms.
He said future post-disaster screening programs should check for "complicated grief" and programs and treatment options should be available long-term because psychological impacts were not limited to the first few years after such events.