Pharmac expects a new hepatitis C drug to lift the cure rate from about 30% to up to 75%.
From 1 September, the State drug agency will fund boceprevir at a cost of $18 million over the next five years.
The drug is for the most common type of hepatitis C and will be made available to patients who test positive for a particular gene.
Hepatitis C is a virus that becomes a chronic infection and can cause fatal liver disease.
Auckland liver specialist Ed Gane said it will also halve the treatment time for many people, from a year down to six months.