The impact of moves to lower the retail price of milk have shown up in the latest Food Price Index.
Fresh milk prices fell by 5.7% in May.
Statistics New Zealand says that's the biggest fall since an 8% drop in September 2006.
Fresh milk prices are more than 7% lower than they were a year ago.
Butter prices also fell by 14% last month. They are now 25% below a year ago, and cheddar cheese prices are 15% lower, compared with May last year.
Meat prices also fell a little last month, but overall, food prices rose by 0.3%.
Seasonal increases in the price of some fruit and vegetables, which were up 3.2% overall, contributed to that.
