The National Association of GPs has criticised the way the Health Service Executive is validating hospital waiting lists and removing patients from the list if they fail to respond to letters quickly.
The Association's President Dr Maitiu O'Tuathaíl said it was a disgrace and that GPs had seen a dramatic increase in these letters.
He described it as a cynical political ploy to manipulate lists, with patients given ten days to respond.
Dr O'Tuathaíl said it was affecting vulnerable people, the elderly, people who have problems reading, foreign nationals and many other groups.
He pointed out that patients may be on holidays or have moved address.
Some GPs have received more than 100 such letters in a week.
Latest national waiting lists show that at the end of June, more than 706,000 patients were waiting for treatment, or to be seen to be assessed.
Of these, more than 511,400 were waiting to be seen at an outpatient clinic by a consultant, having been referred by their family doctor.
The HSE said that hospitals carry out validation of waiting lists, in line with national guidelines, to ensure patients still require their appointments.
It said that last year, almost half a million people did not attend their outpatient appointment and that others could have used these slots.