A third of teenage girls suffer sexual abuse in a relationship and a quarter experience violence at the hands of their boyfriends, a survey suggests.
Nearly 90% of 1,400 girls aged 13 to 17 had been in intimate relationships, the NSPCC and University of Bristol found.
Of these, one in six said they had been pressured into sexual intercourse and one in 16 said they had been raped.
The government is developing guidance for schools on gender bullying but says it is "vital" parents advise children.
A quarter of the girls interviewed for the survey had suffered physical violence including being slapped, punched or beaten, while others had been pressured or forced to kiss or sexually touch.
Only one in 17 boys reported having been pressured or forced into sexual activity but almost one in five had suffered physical violence in a relationship.
Professor David Berridge, from the University of Bristol, described the findings as "appalling".
"It was shocking to find that exploitation and violence in relationships starts so young," he said.
"This is a serious issue that must be given higher priority by policymakers and professionals."
Diane Sutton, head of NSPCC policy and public affairs, said: "Boys and girls are under immense peer pressure to behave in certain ways and this can lead to disrespectful and violent relationships, with girls often bearing the brunt.
"Parents and schools can perform a vital role in teaching them about loving and safe relationships, and what to do if they are suffering from violence or abuse."
The report recommends child protection professionals consider the cases of girls who are in relationships with older boyfriends, with three-quarters in this category saying they had been victims of abuse.
Many girls said they put up with abuse because they felt scared, guilty or feared they would lose their boyfriend.
One told researchers: "I only went out with him for a week. And then, because I didn't want to have sex, he just started picking on me and hitting me."
A spokesman for the Department for Children, Schools and Families said personal, social, health and economic studies - including relationship education - would become statutory for children of all ages by September 2011.
"Parents have a vital role to play in providing information and advice on sex and relationships," he said.
"They should lead on instilling values in their children, but schools have a clear role in giving young people accurate information and developing the skills they need to make safe and responsible choices."