Northland health officials are worried that a cylinder containing potentially fatal gas has gone missing from Whangarei Hospital.
A cylinder of nitric oxide was delivered in May, but could not be found when the hospital's intensive care unit requested it last week.
The toxic, odourless gas can cause serious injury or death if not administered by a medical practitioner.
Northland District Health Board says the gas should not be confused with nitrous oxide, a general anaesthetic, commonly known as laughing gas.
Anyone with information about the gas is being urged to contact police or the hospital.
A spokesperson for Northland District Health Board, Fleur King, says its not known whether the gas has been lost in transit or at the hospital or whether someone has taken it.
Anyone with information about the gas is urged to contact police or the hospital.