Radiation therapy has resumed at Waikato Hospital, after disruptions caused by a major cyber attack last month.
Chief executive Kevin Snee said it was an important milestone for the hospital.
Many staff had been working around the clock to get the machines back online after the district health board's (DHB) computer network was hacked.
Dr Snee said the service would not be operating at full capacity and some patients would continue to receive care in Tauranga and Wellington.
The first treatment began this morning and 22 patients are scheduled for radiotherapy today.
Other services expected to be restored this week include inpatient management, diagnostic, radiology and laboratory services.
Last week the DHB said while it was making significant process on restoring its IT system, it included several hundred servers, many major network sites and thousands of work stations.
The DHB had gained a fuller understanding of what happened and how to safeguard against another cyber attack, Dr Snee said.