Two in five North Koreans are undernourished and more than 70% of the population relies on food aid, the United Nations says.
In a new report, it said most North Koreans also lacked access to basic healthcare or sanitation.
Diarrhoea and pneumonia are the two main causes of death for children under five, the report said.
Humanitarian needs had been exacerbated by "recurrent natural hazards", such as frequent floods and drought.
"Amidst political tensions, an estimated 18 million people across DPRK [North Korea] continue to suffer from food insecurity and undernutrition, as well as a lack of access to basic services," the UN report said.
"Furthermore, 10.5 million people, or 41% of the total population, are undernourished."
Isolated North Korea, which has a population of about 25 million, has faced significant food shortages for years.
Hundreds of thousands are believed to have died during a widespread famine in the 1990s.
τυπικος κομμουνιστικος επιγειος παραδεισος...