A Crown Monitor has been appointed to support the Canterbury District Health Board.

Dr Lester Levy, who's previously been the chair of three DHBs, will start in the role immediately.

Health Minister David Clark says Canterbury DHB has the largest deficit in the country, with a forecast to end the financial year in the red by more than $103 million.

He says that's not sustainable, however he recognises the challenges the region's faced.

CDHB Board Chair Doctor John Wood says Dr Levy will help improve their financial performance in turn helping the DHB respond to its many challenges.

He says these include the aftermath of the earthquakes, redevelopment needs and the recent impacts of the March 15 terror attacks.