Half of young women in Oxfordshire missing smear tests.
More than half of women in their 20s in Oxfordshire have not had cervical smear tests, NHS bosses have said.
Health managers at the county's primary care trust said out of 25,000 25 to 29-year-olds offered the test, 14,000 have not had it.
A campaign has begun in an effort to persuade more women to have the test to try to reduce their risk of developing cervical cancer.
NHS bosses said screening could prevent 75% of such cancer cases developing.
In Oxfordshire, they said, the number of 25 to 29-year-old women that have smear tests was very low.
They said the figure for older age groups was higher, with 73% of 30 to 34-year-olds and 79% of 35 to 39-year-olds having the tests.
Women are offered the tests every three to five years.
Shakiba Habibula, assistant director of public health for Oxfordshire Primary Care Trust, said that it was "quite concerning" that so many of the 25 to 29-year-old age group of women were not taking up the offer of the screening.
She said: "Many women in this age group think they are too young to think about cancer, they think it only happens to older women."
She added that reality television star Jade Goody's experience has had an effect on women under 25 coming forward, but not as much on the 25 to 29-year-old age group.