More than a quarter of women who do not go for regular smear tests are unaware they exist, research suggests.
A new survey of 3,113 women found that of 793 who were not up-to-date with screening, 28% were unaware of smear tests, 15% had decided not to attend and 51% were intending to go but were currently overdue.
Younger women were more likely to be unaware of screening, while older women were more likely to have decided not to be screened, the study found.
Women from ethnic minority backgrounds, some of whom had English as a second language, were also more likely to be unaware of screening than those who were white.
A lower socio-economic status also had a negative impact on cervical screening.
Health experts are becoming increasingly concerned about the continued drop in the number of women attending smear tests.
In England, women are invited for screening every three years between the ages of 25 and 49, and every five years if they are aged 50 to 64.
Those over-65 are only screened if they have not been tested since they were 50 or if they have had abnormal results.
Around three-quarters (73% to 78%) of eligible women in the UK are up to date with cervical screening but this is a fall compared with recent years.
Around 3,200 women are diagnosed with cervical cancer each year in the UK and around 900 women die from it.
The new study was funded by Cancer Research UK and carried out by scientists at University College London (UCL).
Dr Jo Waller, from the UCL Institute of Epidemiology and Health Care, said: "It's worrying that so many women don't know about cervical screening.
"This study also suggests that many women, particularly younger ones, don't get round to cervical screening, even when they intend to go.
"The results around lack of awareness suggest that campaigns using TV, radio, social media or face-to-face visits may be better ways of communicating with women about screening than relying on letters in the post, which is the current method.
"And for women who find making an appointment stays on tomorrow's to-do list, simple steps such as extra reminders, or specific appointment slots for first-time screenings could really make a difference and potentially save lives."
Sarah Williams, health information manager at Cancer Research UK, said: "This study shows that many women who aren't up to date with screening haven't deliberately decided not to attend.
"We may need to be more creative in our efforts to help specific groups of women, rather than resorting to conventional 'one-size-fits-all' awareness campaigns.
"Cervical screening prevents an estimated 2,000 deaths each year in the UK, so it's imperative that we do all we can to inform women about it and to make it easier for them to make well-informed decisions about whether to attend, and to take up their invitations if they decide to accept them."
Dr Anne Mackie, director of screening for Public Health England, said: "We're supporting local services to encourage more women to attend screening through clearer information.
"We have also asked the independent expert Screening Committee to consider the merits of at-home self-testing for women who are not taking the test."