Sales in the manufacturing sector fell a seasonally-adjusted 0.7% the three months to the end of June, the first quarterly fall since September last year.
Excluding meat and dairy, sales edged up 0.3%, the weakest growth in three quarters.
The slowdown coincided with a 3% gain in the New Zealand dollar.
A union says the manufacturing slowdown will worsen if the Government fails to provide more support to industry to counter the high dollar.
National Distribution Union general secretary Robert Reid says wood processors in particular are being hit hard by the dollar and high log prices.
He estimates 200 jobs have been lost in that sector alone in last two months.
Mr Reid backed calls from the Manufacturers and Exporters Association for the Reserve Bank to do something to bring down the Kiwi.
Goldman Sachs economist Philip Borkin says already-struggling manufacturers face heavier weather in the months to come.
He says the high Kiwi and turmoil on global markets are set to weigh on future sales.