Hospitals and GP practices run by NHS Lanarkshire have been disrupted by a cyber-attack, officials have said.
The health board confirmed malicious software had been detected in IT systems, causing appointments and procedures to be postponed.
Chief executive Calum Campbell said the board "took immediate action" to put a security solution in place, and was working to minimise impact on patients.
It is unclear at this point whether the health board was deliberately targeted.
NHS Lanarkshire was one of the worst-hit health authorities in Scotland in the widespread cyber-attacks in May.
However, a spokeswoman for the health board said the current issues were "not on the same scale".
She said a number of appointments and procedures had been postponed as a result of the current issues, but there were "no concerns around emergency treatments".
Mr Campbell said: "We have detected some incidences of malware and took immediate action to prevent this spreading while we carried out further investigations.
"We are currently putting in place a solution from our IT security provider.
"While the issue is being resolved, our staff have been working hard to minimise the impact on patients and we apologise to anyone who has been affected."