The manufacturing sector is back in the doldrums after a short-lived improvement.
The BNZ-Business New Zealand Performance of Manufacturing Index (PMI) fell to 49.3 in December from 51.2 the month before.
A reading above 50 indicated expansion.
Three of the index's components fell, with a drop-off in new orders and a slowdown in production weighing heavily on the sector.
BNZ senior economist Craig Ebert said the result was disappointing.
"After a couple of months flirting with positivity, New Zealand's PMI dipped back just below the breakeven line again in December."
The industry showed signs of improvement late last year, moving back into expansion after three months of contraction.
The December reading was at odds with a business confidence survey released earlier this week, which showed a rebound in manufacturers' sentiment.
Ebert said that survey might suggest the industry was through the worst, and output and profitability would soon pick up.