The NHS in Scotland should manage its £5bn assets - including land, buildings and equipment - more efficiently, auditors have warned.
Almost a third of the NHS estate needs repairs, there is a maintenance backlog of at least£512m - based on information from 16 NHS bodies.
The investigation revealed 23 per cent of the estate was underused, 3 per cent was empty and 11 per cent was overcrowded.
The Audit Scotland report published last week said it was hard to get a full picture because boards could not provide enough data.
Scotland auditor general Robert Black said: "This is an area where the NHS may be able to achieve greater efficiency but it is difficult to say on what scale because of the lack of information."
Available data indicates nationally 30 per cent of NHS estates need upgrading, with 1 per cent in "serious risk of imminent breakdown".
NHS Lothian had 44 per cent needing upgrading and 4 per cent in a seriously bad condition. NHS Lothian director of facilities John Jack said: "We recognise some buildings are showing their age - that's why we've already announced a capital investment programme in excess of£240m [to] deliver upgraded facilities right across NHS Lothian."
Although almost all NHS bodies had surveyed their estate in the last five years, only 11 out of 23 returned data on how well it was performing. Based on that information, a fifth was not suitable for the purpose for which it was being used and 3 per cent was "unacceptable".
NHS Grampian has the highest backlog at£140m. A spokeswoman said capital investment had been slow over previous decades, but was being addressed through the NHS Grampian investments plan, which expects investment in excess of£300m over the next 10 years.
The Scottish government said significant investment was being made in new and replacement facilities, and through maintenance.