MEDICAL card holders are 50pc more likely to have an abnormal test result after undergoing cervical screening.
The Dublin Well Woman Centre said this rate of abnormal smear test results – which need further investigation – is "disproportionately higher" among medical card holders.
A cervical screening test is a method of detecting abnormal (pre-cancerous) cells in order to prevent cervical cancer.
Chief executive Alison Begas said an analysis of smear test results taken by the centre shows that, in every age category from 25 to 50, a woman with a medical card is 50pc more likely to need to be referred for further tests.
"The figures show shocking health inequality," said Ms Begas, whose clinics take 9,000 tests every year.
The figures show medical card holders at the Well Woman centre in Coolock for a test are more likely to require a colposcopy than private patients at its three Dublin clinics.
"Our clinical experience demonstrates very clearly that poorer women are significantly more likely to have abnormal smear results that require further investigation.
"For that reason, it is crucially important that CervicalCheck, the free national screening programme, continues to target women from the most 'at-risk' groups for cancer screening,'' said Ms Begas.
Dr Shirley McQuade, medical director, said: "The Human Papilloma Virus (HPV), which causes cervical cell abnormalities, is more prevalent in smokers. It is also more prevalent across groups who experience first sexual intercourse at an early age."
Contact CervicalCheck:1800 45 45 55