Twenty vials of anaesthetic drugs are missing from Hutt Hospital.
They were taken last Tuesday from a resuscitation bay in the hospital's emergency department.
The drugs were in liquid form stored in glass or plastic vials.
They were taken while staff were attending a patient in the resuscitation bay, Hutt Valley DHB Chief Medical Officer Sisira Jayathissa said.
"These drugs are dangerous, and could cause harm or even death if taken outside a clinical setting.
"I urge anyone who has these drugs, or comes across them, to immediately hand them in to Hutt Hospital, any New Zealand hospital, or the Police," she said.
The drugs were in the resuscitation bay while the patient was being cared for and are used for general anaesthetics.
They can possibly be sought for recreational purposes, a DHB spokeswoman said.
An investigation into the incident is underway.
A police spokeswoman also said police were aware of the incident and were "following lines of inquiry".
"We urge anyone with information about this to contact police on 105 or if they come across the vials to hand them into police immediately."
The drugs are:
• Propofol (anaesthetic)
• Etomidate (anaesthetic)
• Rocuronium (muscle relaxant/anaesthetic)
• Suxamethonium (muscle relaxant/anaesthetic)
• Tracurium (muscle relaxant/anaesthetic).