The HSE has decrypted one-third of its IT servers following last month's cyber attack.
Over 50,000 end-user devices are also connected, out of a total of more than 88,000.
However, it says health services are still experiencing widespread disruption.
It's now 4 weeks since its systems were targetted by criminals in a ransomware hack.
The head of the HSE says the cyberattack will continue to pose extreme risks to many healthcare settings.
HSE Chief Operations Officer, Anne O'Connor, says they could be dealing with IT issues for many more months.
Ms O'Connor says there is still a long way to go before they completely recover.
She says it's worth pointing to a recent EPA cyber attack in Scotland, with the group still dealing with the fall out from that 6 months on.