Patients who fail to cancel their appointment until the day they are due to attend are costing NHS Forth Valley hundreds of thousands of pounds.
They are also denying 600 people per month the chance to be treated more quickly.
So far this year 5,500 patients have cancelled at the last minute, leaving NHS Forth Valley to foot a £660,000 bill.
This is in addition to the £4 million annual costs run up by those who simply fail to turn up - just over one in ten of all outpatient appointments.
The figures have been described as ‘concerning’ by NHS Forth Valley’s Medical Director Andrew Murray.
He said: “Cancelling or moving an appointment on the day is pretty much the same as not turning up as it doesn’t allow us to fill the slot.
“I appreciate that sometimes there are genuine reasons for not keeping an appointment but, where possible, we would ask people to let us know beforehand. This would give us the chance to reschedule and allow someone else to attend.
“I realise that patients may think they are doing the right thing letting us know they can’t attend that day, but by then it is too late then to contact others who are waiting for treatment.
“It’s also important to remember that a last minute cancellation could potentially delay any future treatment.”
Procedures have been set up to make it easier for patients to cancel or rearrange their appointments.
This includes an appointment telephone reminder system for the majority of consultant led outpatient clinics, while a text reminder service will soon be in place.
People can also ring the number on their appointment letter or cancel their appointment online by completing a short form on the contact section of NHS Forth Valley’s website (www.nhsforthvalley.com).
Meanwhile a new procedure is being introduced for some specialities .
Patients who are waiting will be contacted to check the appointment is still required.