The Public Health Agency says 150 women have been recalled amid “possible shortcomings” in their cervical smears.
The tests were carried out by one healthcare worker at two doctors' practices one in Belfast and one in Newtownabbey.
Concerns relate to the technique used.
Dr Tracy Owen from the PHA said: "We understand that the women who are receiving these letters may be anxious, but we would like to reassure them that this is a precautionary measure and would urge them to accept the invitation for a repeat test."
Cervical screening aims to prevent cancer.
Women aged 25 to 49 are routinely invited for cervical screening every three years, and those aged 50 to 64 are invited every five years.
The issue was identified within a GP practice through good vigilance, monitoring and audit processes, the health service said.
A review team was established by the Health and Social Care Board (HSCB) and PHA and 150 women registered with Abbott's Cross Practice in Newtownabbey and Dr McKenna's Practice in Thames Street, Belfast, have been sent invitations by their GPs for a repeat test.
A statement said: "The PHA and HSCB have been made aware of possible shortcomings in the technique used to take cervical screening tests at two GP practices.
“This issue affects a small number of women whose tests were taken by one particular healthcare worker."