More than one million GP appointments were missed in Scotland in a year, costing the NHS an estimated £16m, according to a survey.
Many GPs think patients should pay for missing appointments
Just over half of the doctors who took part in the study said they would be in favour of charging patients who do not turn up at their surgeries.
However, the research also showed that the number of missed appointments had fallen by 500,000 on the previous year.
The results were released at the start of the "Keep It Or Cancel It" campaign.
It includes new guidance for GPs to help them manage missed appointments, as well as posters to remind patients to cancel unwanted appointments.
The survey was conducted among 707 GP surgeries throughout the UK - including 49 in Scotland - between 1 July and 1 August.
Doctors said that about half of patients forgot their appointments and 40% thought they "felt better" so simply chose not to turn up at the surgeries.
It has been estimated that Scotland's no-show patients cost the health service at least £16m.
The figures were drawn up by the charity Developing Patient Partnerships (DPP) and the Institute of Healthcare Management.
Dr Mary Church, of the British Medical Association (BMA), said: "Many GP practices are doing all they can to improve access for patients but still a high volume of appointments are being missed.
"This forgotten million missed appointments leads to unavoidable inefficiencies in GP services and wasted opportunities to provide care for patients who need care. One million missed appointments is a terrible waste to the NHS and patients."
DPP spokesman Dr Terry John added: "Consistent reinforcement of the 'Keep It Or Cancel It' message is crucial.
"Most practices believe public awareness campaigns can help combat the problem, which could explain why almost a third of practices said they have seen a reduction in missed appointments over the last two years.
"There is no reason why this figure can't climb, especially with the new guidance that highlights simple measures that practices can take to address the problem."
Most dentists charge for missed appointments, and just over half of the doctors surveyed said they would support similar measures at their surgeries.
The Scottish Executive said it was piloting new schemes to combat the problem - including one where patients are reminded of their appointment by text message.