NSW Health Minister Brad Hazzard has promised an investigation after sensitive patient records were found in an abandoned building.

More than 1,000 confidential medical records were found on the floor of the former site of the Garrawarra Centre for Aged Care in Helensburgh, the ABC reported on Thursday.

"To those people whose medical records were put in such storage arrangements in the early 2000s, I express my sincere apologies and can assure them and their families I will get NSW Health to do whatever I can to rectify the situation," Mr Hazzard said in a statement.

Opposition Labor health spokesman Walt Secord called on NSW Health to guarantee all family members associated with the medical records - which date from 1992 to 2002 - will be formally notified of the breach.