Workers' productivity dropped slightly last year after a significant improvement the previous year, official figures show.
Workers' productivity fell point 0.1% in 2011, the third decrease the past five years.
It followed a healthy 3.5% increase in 2010.
Productivity growth over the past six years was just 0.5%, which Statistics New Zealand says is the weakest period of productivity growth for any economic cycle in more than 30 years.
The decline in 2011 was a result of firms' labour inputs rising at a faster rate than production, the department said.
Productivity that year was not helped by a drop in the amount of equipment used by workers.
The decrease came as investment by firms failed to keep up with the increase in workers employed.
The figures cover 80% of the economy, excluding government administration, and the health, education and defence sectors.