The HSE says approximately 800 women were not issued Cervical Check results due to an IT issue.
The health authority has apologised saying some results letters were not issued to GPs either.
The tests involved in this latest Cervical Check problem were mainly repeat test that were carried out between October 1 st last and June 25th this year
The Head of the National Screening Service says the women involved were written to on July 1st and told to contact their GP for their results.
The problems stem from a laboratory operated by Quest Diagnostics in Virginia in the US.
THe HSE says an IT update, to allow results letters be sent to women and reports to their GPs, was slower than expected to implement
Some GPs and nurse practices say they have not reveived results in recent days and the HSE the lab involved is now issuing letters and reports manually
The HSE says Quest Diagnostics has told it that all IT updates and testing on the system will be complete within in two weeks and the HSE is closely monitoring the situation.