Foster children suffer mental health problems far more commonly than other children, new research has revealed.

The research, by Professor Michael Sawyer and colleagues from the Children, Youth and Women's Health Service and University of Adelaide, is reported in the latest Medical Journal of Australia.

It reveals that many children experience mental health problems in a welfare system that is seriously in need of more mental health support services.

Funded by the Australian Rotary Health Research Fund, the research compared the prevalence of mental health problems among children and teenagers in home-based foster care with those among children in the general community.

"We found that the prevalence of mental health problems experienced by children and adolescents in home-based foster care was two to five times higher than that in the general population," says Prof Sawyer.

The study found that attention and social problems were more common than anxiety and depression, and were more prevalent in younger children.

"Severe disruptive behaviour is of particular concern as it can continue into adulthood and is a source of significant economic burden for the whole community," says Professor Sawyer.

Rates of suicidal behaviour for those in home-based foster care were found to be much higher than those recorded in the community, with 6.7 per cent of 13-17 year olds reporting a suicide attempt that had required medical treatment.

Caregivers who were surveyed reported that 53.4 per cent of children in care needed professional help for their emotional and behavioural problems, but only 26.9 per cent had obtained help.

"Our findings provide a major challenge for the community and for welfare services," says Prof Sawyer.

"It is unrealistic to expect volunteer caregivers to provide 24-hour care and support for these young people unless they receive high-quality professional support and adequate respite.

"There is a great need to develop and evaluate new interventions to address the mental health problems experienced by these young people."