Universal health care should be available for all children up to the age of 18, the Child Poverty Action Group says.
That includes GP visits, prescriptions, oral health, and vision and hearing care, the charity says in outlining its health priorities for the 2017 general election.
CPAG says the number of children admitted to hospital for preventable illnesses linked to poverty and bad housing has been rising since 2000 and is now around 40,000 annually.
It believes such admissions could be halved in five years and the chances of preventable illnesses affecting children could be reduced in the long term.
"The shameful facts are very well known," CPAG health spokesperson Professor Innes Asher said.
"What New Zealand needs is a comprehensive set of policies to lift all our children out of poverty and into healthy housing, with the basic health care they need at all times."
CPAG had made a number recommendations to support the reduction in child hospital admissions, including the call for universal health care.
Among others is developing a coordinated framework for all children in health care from pregnancy to adulthood to identify those in greater need.
It also wants provision of universal antenatal care and maternity services, and an increase in the number of schools with school-based health services.