Seventy per cent of mothers have experienced violent behaviour or threats from their adolescent children, a study reveals.

The behaviour reported by mothers included physical violence, intimidation, psychological torment, and verbal and financial abuse.

The findings are based on a pilot study of 129 households which is the forerunner to a survey of 6000 homes to be conducted soon in Sydney's western suburbs.

Professor Lesley Wilkes, acting dean of the school of social and health sciences at the University of Western Sydney, was not surprised that 70 per cent of mothers had experienced threats or violence.

She said the problem was widespread but hidden because mothers were reluctant to discuss it. Mothers often felt guilty or that society was blaming them for their children's behaviour.

"Society says 'If you allow your child to bash you, it's your fault'," she said.

Michel Stewart, who is undertaking the study for her PhD, said the finding of 70 per cent was significant because people believed adolescent violence and threats were not common and victims felt they were alone in their experiences. "For this reason, it can be difficult to get women to be candid about their experiences," she said.

"We are interested in finding out how much of this occurs in the community with an aim to developing support services for mothers of teenage and young adult children."

The three-year study - the first of its type in Australia - is funded by the Australian Research Council and is being conducted by the University of Western Sydney's School Of Nursing, Family And Community Health and the Sydney West Area Health Service.

A report by nursing associate professor Barbara Cottrell to Health Canada recently described parental abuse as a well-kept secret that had striking similarities with the situation 20 years ago when spousal abuse was considered rare. "To help families and stop parental abuse, we have to break the silence that surrounds it," she said. "Because parental abuse is still not recognised, it is often considered acceptable behaviour. The first step to ending the abuse is recognising that it is abuse."

Victims of adolescent violence and support agencies are critical of the lack of services available to battered parents in Victoria.

One single mother sought help from Victoria's Department of Human Services to protect her and a younger daughter from her teenage daughter's violence, only to be sent a standard letter saying husbands and wives should not argue in front of their children.