Patients miss over 11m GP appointments and 5m practice nurse appointments each year in the UK, a survey suggests.
Missed appointments cost NHS money
The poll, by Developing Patient Partnerships, found even offering same day appointments was often not enough to solve the problem.
London had the worse problem, followed by the North West of England, and the West Midlands.
Most of the 329 GP surgeries who took part said missed appointments caused them problems.
The survey also found that 30% of practices said there was an increase in missed appointments when patients were able to pre book appointments.
Dr Chaand Nagpaul, GP and DPP Spokesman, said: "People are still missing appointments even when they make them for the same day.
"Appointments cost the NHS money. Missed appointments are a waste of valuable resources.
"With the move to offer the public more services, and more expensive services through the GP, the issue of missed appointments is an increasing problem for practices."
Knock on effect
Nurse practitioner Anne Baird said missed appointments meant all patents ended up having to wait longer to be seen.
"Sometimes an entire family may book in for their holiday jabs and then fail to turn up - leaving the nurse with several wasted appointments.
"Nurses are increasingly managing the long-term care of patients with chronic illness, such as diabetes. Often these patients are given a double appointment for a full review.
"Again, if appointments like these are missed, it's extremely frustrating for nurses, who want to deliver the best possible care to all their patients."
Danny Daniels, Chair of the National Association for Patient Participation (NAPP) said more research was needed to pin down the causes, and to develop effective ways to tackle the problem.
"It is important to note that the percentages of missed appointments will differ widely depending upon the location of the surgery, the individual surgery's approach to 'Did Not Attends', the patients' list profile and a whole number of other factors including whether the practice has a patient group in place."
Dr Greg Graham, GP from a surgery in Pontypool, South Wales, said his practice took a tough line with people who did not turn up for appointments.
Patients who fail to attend for a second time get a warning letter, then if they fail to attend for a third time, and do not have a good excuse, they are struck off the practice list.
"I can be sitting in the middle of surgery, and two people do not turn up in a row," he said.
"I've got a blank space and my poor receptionist outside is having to tell patients they have got to wait another two days to see a doctor.
"If people had been decent enough to tell us they were not going to come those people could perhaps have been slipped in at ten minutes notice."