It found the age at which people first have sexual intercourse has dropped over the past 50 years from 18 for men and 19 for women to 16 for both men and women.

Young people are also experimenting with oral sex at a younger age.

"The declining age at first intercourse ... highlights the need to urgently review the teaching of sex education in primary school," the report said.

The study found, while most people identify as heterosexual, Australians are not generally conservative when it comes to sex.

Three quarters believe sex before marriage is acceptable and some reported using sex toys, watching X-rated films and - among men - paying for sex. Less than one in 20 had engaged in phone sex, role-play, sadomasochism or bondage and discipline.

Those in regular heterosexual relationships for more than a year had sex 1.84 times a week but 85 per cent said they wanted sex at least twice a week.

Five per cent of men and three per cent of women have had sex with someone other than their regular partner in the past year.

Nine per cent of men and 15 per cent of women had experienced same-sex attraction.

Dr Anthony Smith from the Australian Research Centre in Sex, Health and Society at La Trobe University said the report showed Australia's sexual culture had changed markedly.

He said Australians were having sex earlier than their parents and with more partners.

While people now aged in their 50s reported having two or three sexual partners in a lifetime, it was not uncommon for people in their 20s and 30s to report 10, he said.

Dr Smith said these trends were placing people at increased risk of sexually transmitted diseases. According to the report, nearly one in five Australians had a sexually transmitted infection at some stage in their lives.

Dr Smith also high lighted as an area of concern findings that one in five women and one in 20 men had been forced or frightened into doing something sexual.