Some radiation therapy cancer patients are now having their treatment at Waikato DHB after the service resumed today.
Last month, the Waikato DHB was crippled when a cyber attack brought down all of its systems.
The DHB has several hundred servers, many major network sites and many thousands of workstations, numerous mobile devices and specialist medical equipment.
The DHB was working closely with international specialist services to systematically test and secure all devices and systems before each one was reinstated.