Two hospitals in Oxford are set for months' worth of surveys and work on their cladding.
Oxford University Hospitals NHS Foundation Trust has said some of the material covering The Children's Hospital at the John Radcliffe, and the Cancer and Haematology Centre at the Churchill, may need replacing.
A routine survey at Oxford Children's Hospital has found that the building's facades were not made with the cladding that was specified in their original design.
Sections of panelling in four areas of the hospital need to be taken off, and new cladding will have to be designed.
Over at the Churchill Hospital, the work is twofold.
Borescope surveys are being done around the full perimeter of the building; with sections of cladding being taken off two parts of the front of the building next to INtensive Care and the North East Stairwell.
This work is set to finish early next year.
Jason Dorsett, Chief Finance Officer said: "While both these projects involve cladding, the requirements at each location are different.
"The Trust has been working closely with both our PFI providers to ensure that these buildings are safe and that the remedial work can be done with the minimum disruption to our patients, visitors and staff.
"In both cases, the costs of the work will be met by our PFI providers."
"I would like to assure patients, visitors and staff that the buildings are safe for use and that current fire safety standards are being met at both hospitals."
Rob MacDougall, Chief Fire Officer at Oxfordshire County Council Fire and Rescue Service said: "We have been working closely with the Trust and its PFI providers to ensure that patients, staff and everyone else using these premises are safe while this work is carried out.
"A comprehensive range of fire safety measures at the Children's Hospital are in place and we are satisfied with the arrangements."