The trade deficit has widened due to reduced volumes and lower export prices.
Official figures show the deficit stood at $437 million in August, compared with a revised shortfall of $183 million in the previous month.
Statistics New Zealand says exports fell 12% to $3.1 million with prices falling for meat, dairy and forest products. Imports fell 4% to $3.6 million.
ANZ economist Mark Smith says August is normally in deficit, as it is a seasonal lull for many agricultural products.
Mr Smith says the deficit reflects that global demand has eased for commodities.
On an annual basis, the trade surplus stood at $866 million, the highest surplus since 2002.