The Council of Trade Unions says the small percentage of workers on collective bargaining agreements is a poor reflection on the country's labour record.
An International Labour Organisation study shows that about 15 percent of workers in New Zealand have collective agreements, compared to nearly 100 percent in Austria and France.
The study shows the number of New Zealand workers on collective bargaining agreements is less than in Albania, Russia and Bulgaria, and on a par with the United States.
Council of Trade Unions president Richard Wagstaff said the figures showed that more needed to be done to increase the number of workers on collective agreements.
"It reflects badly on us as a country in terms of the support we have for people working in unions and banding together to improve their conditions, it's another statistic that really needs to be confronted."
Mr Wagstaff said the figures were disappointing, especially as New Zealand had a larger union presence than countries which have about 90 percent of workers on collective agreements.
He said it showed employment law needed changing.
However, Employers and Manufacturers Association Northern chief executive Kim Campbell disagrees.
He said the current coverage rates were satisfactory.
"Participation in collectives and unions in New Zealand is relatively low and that reflects the great success of the Employment Relations Act and the fact is most people get what they need through personal negotiation.
"Bearing in mind that whilst we don't reflect the overseas situation, that we have other protections which are not available elsewhere."
Mr Campbell said New Zealand had a different work environment with things such as the employment court and a vigourous personal grievance industry.
Business New Zealand manager of employment relations policy Paul McKay said the number of workers on collective agreements was a reflection of where countries were at.
Mr McKay said it was not a push back against unionisation but a result of the freeing up of competition and trade.
He said people would only be collectivised if they saw it as a better option.