A significant number of women in their early 20s still do not know how their reproductive systems work, according to the Irish Family Planning Association.
The IFPA has found that many women from 20 to 24 who attend their facilities do not know the terminology for their reproductive organs and are not informed about contraception and sexually transmitted infections.
Many mistakenly believe the contraceptive pill protects them from sexual diseases.
Children may be becoming sexually aware much earlier now, but it's not surprising that some people still do not have a basic grasp of how reproduction works, said Ms Catherine Heaney, IFPA assistant chief executive.
Many teenagers are not educated in the home about sexual matters, and because many schools have not adopted the Relationships and Sexuality (RSE) Programme, students are not getting the information at school.
If they do not attend biology or home economics classes, or drop out of school early, they miss even the most basic sex education, she said.
Last week's Prime Time survey on the sexual habits of 18- to 30-year-olds found that 30 per cent of those surveyed had received no sex education at home. Of those who did, mothers were far more likely than fathers to broach the subject.
Some 41 per cent said they had not received sex education at school. Fewer than one in three people found sex education in school "fairly" or "very" informative.
The survey found that those who received little or no sex education were more likely to lose their virginity earlier, have more sexual partners and engage in unprotected sex.
The Government introduced the Relationships and Sexuality Education (RSE) programme to schools in 1995. But by August 2000, more than two-thirds of primary schools had not implemented it.
Just over 41 per cent of secondary schools had introduced the programme to all classes.
The IFPA is now calling for a detailed review of the RSE programme. Ms Heaney says the agency strongly supports the programme but is concerned that not all schools are implementing it. "We have to find out what the programme is delivering. Are there information gaps? Programmes like this need constant monitoring," she said.
Ms Heaney believes a comprehensive education programme needs to be available outside schools to cater for those who have fallen through the gaps.
She calls for the establishment of one-stop shops offering advice and information on contraception, sexual problems and crisis pregnancy.
She is also seeking a free help-line to provide non-judgmental information on these issues.
Teenagers in disadvantaged families are "highly unlikely" to ask for the family medical card to visit the doctor on a sexual health matter, Ms Heaney said.
"Young people are often reluctant to approach their family doctor for emergency contraception, for instance, and women with a crisis pregnancy often make the journey to the UK for abortion without any prior counselling."
Meanwhile, Mr Gay Mitchell, Fine Gael's health spokesman, says there is "something approaching an epidemic" in the sexual health of younger people.
Whatever the outcome of the election, he says Fine Gael will be asking the joint Oireachtas committee on children to carry out an inquiry into the cause of the increase in sexually transmitted diseases and to report to the Dáil within three months.
