The New Zealand Blood Service says it needs more donors if it is to remain self-sufficient.
Currently the service has 117,000 donors who help save the lives of 30,000 people every year.
Communications manager Asuka Burge said with a growing and ageing population, the country was facing higher-than-ever demand.
She said if more people were not encouraged to join the donor registry, New Zealand might not continue to be self-reliant for blood and plasma.
“If we can’t meet demand, it means we are going to be forced to compete in the global market, for particularly plasma products.
“We don’t want to do that. It’ll make things very challenging, so we are asking people ... Kiwis to help other Kiwis,” she said.
Burge said as part of National Blood Donor Week they were calling for 40,000 more New Zealanders to become blood donors.
Less than 4 per cent of the eligible population donated currently, she said.