Ngati Ranginui says young people make up the majority of those missing from its iwi register.
The Tauranga-based iwi has launched an advertising campaign to sign up the more than 5000 iwi members who have not registered.
That represents about half the total Ngati Ranginui population of 10,000.
Chairman for Te Roopu Whakamana o Ngati Ranginui, Antoine Coffin, says it's important for the future of the iwi that the younger generation be part of decision making on the tribe's treaty claims.
He says high-profile singers and artists from the iwi are being used in the advertising campaign to encourage the missing iwi members to sign up.
They must register before 30 April if they want to vote on the Treaty claims offer from the Crown.