Detection dogs were brought into Auckland's Ronald McDonald House on Wednesday after staff became suspicious someone had brought drugs in.
The sweep was announced in a letter sent out to families staying at the Auckland house on Wednesday, telling families that "unfortunately is has been necessary to bring the drug detector dogs through the house today".
"We treat the breaking of any house rules very seriously, as these rules are in place to ensure the safety of all families and their comfort while staying at Ronald McDonald House," the letter read.
The houses in Auckland, Wellington and Christchurch are a home away from home for sick children and their whanau during hospital treatment.
When asked by the Weekend Herald, a spokeswoman said there had been some suspicion someone had drugs on the property but she would not be drawn on what specifically caused staff to bring detector dogs in.
She also did not say what kind of drugs were suspected to be in the house.
No drugs were found during the search.
Police said they had no record of the incident and a private company, New Zealand Detector Dogs, had been used.
Infrequent drug checks of the house were part of normal procedure, the spokeswoman said, however when pressed she admitted this was not a routine check.
"They had reason to believe that someone was in the house who had drugs ... they just had a suspicion of it," she said.
"[Drug detectors] came in and they found nothing."
The Auckland house had about 47 families staying in it at the moment and their safety was the organisation's top priority.
Sometimes one family having a suspicion that another might be using drugs was enough to take action - as a precaution, she said.
New Zealand Detector Dogs managing director Janet Williams declined to comment on the matter, saying the company did not give information about the jobs they went on.