Unions say New Zealand still has a huge amount of work to do on health and safety
International Workers' Day, or May Day, is being marked around the world on 1 May.
It celebrates workers' rights and struggles.
Council of Trade Unions president Richard Wagstaff said that New Zealand has made advances in pay equity but he said big improvements are needed to keep workers safe.
"The Pike River tragedy, that was a big wake-up call to New Zealand, and a lot of work's been done as a result of that, but we are not really seeing the results that we all want.
"We had a timely reminder, obviously, in the last couple of weeks with the fatalities in the port industry, and we really need to step up in a big way."
There were two port worker deaths within a few days in April.
Wagstaff said New Zealand has double the number of work fatalities per capita of many other countries including Australia and the UK.