Most GPs in the UK gave up responsibility for out of hours care
Too many people in England receive poor quality out-of-hours doctors' services, the Patients Association has warned.
In some areas, a fifth of patients described the service as "poor" or "very poor". Some 1.1m patients responded to the government survey.
Richmond and Twickenham and Hartlepool were among the poorest, with Central Lancashire and Plymouth among the best.
Ministers have given trusts until the end of the year to follow strict new guidelines on out-of-hours care.
And campaigners have described the current system of providing after-hours GP cover as "an accident waiting to happen".
The survey follows the death, in 2008, of 70-year-old David Gray, who died after he was treated by a German doctor with no experience as an NHS GP.
PATIENTS' WORST SIX
Richmond and Twickenham
Dr Daniel Ubani, who spoke poor English and who was exhausted after commuting hundreds of miles from his home in Germany, had been employed by a private company to provide emergency out-of-hours cover.
He gave Mr Gray an overdose of diamorphine and was later described as "incompetent" by a coroner who also called for the reform of the out-of-hours care system.
In 2004, the overwhelming majority of GPs across the UK gave up responsibility for organising out of hours care when a new contract allowed them to opt out.
'Accident waiting to happen'
The study saw some 2.8m survey forms distributed with a response rate of 40%.
Patients were asked to say if they thought the service was very good; good; neither good nor poor; poor; or very poor.
Richmond and Twickenham Primary Care Trust had the worst results for patients dissatisfied with out-of-hours care, with 21% of those who responded saying the service was poor or very poor.
Hartlepool was next, with 20%.
However, in Central Lancashire, 72% said the service was good or very good, while 77% said the same in Plymouth.
Across England as a whole, 65% of those who had used the service in the past six months said their out-of-hours care was good or very good, while 13% regarded it as poor or very poor.
But of those who had been prescribed or recommended medicines by out of hours GPs, 15% said they found it not easy or not at all easy to get hold of the drugs.
And some 35% of all those who took part in the survey said they did not know how to contact their GP out of hours.
In many areas, new contracts for evenings and weekends were taken up by private companies, although GP collectives also run some services.
Kieran Mullan of the Patients Association said ministers should do whatever was necessary to ensure that promises made nationally were delivered locally.
He told the BBC: "We know that the primary care trusts aren't doing a good job in all cases and I think that the government have to take some responsibility for ensuring that they do."
Peter Walsh, of Action against Medical Accidents, said in some areas the system is not fit for purpose.
He told the BBC: "We have adults with strokes, heart attacks where the symptoms haven't been recognised.
"The system we have at the moment is an accident waiting to happen we are fortunate that we have not had more incidences than we have had so far."
Health Minister Mike O'Brien told the BBC provision is still too patchy and that patients need to know their doctor is competent.
He said: "There are a whole series of steps being taken, I'm not satisfied its good enough yet.
"I want by the end of this year, no longer, for it to be good enough for me to know that if I or you call out an out of hours doctor they are competent and they won't kill somebody."
The NHS confederation which represents Primary Care Trusts accepts the system had serious failures, but says most out of hours services do a good job most of the time, and they say new guidelines and practices are improving the quality of out of hours care.
But Dr Stuart Gray, a GP and Mr Gray's son, said he was not convinced the system had been fixed.
He told the BBC: "There is nothing to suggest there aren't other doctors like Dr Ubani, the doctor that killed my father in the system, inadequately trained and unable to converse in English, at this moment in time delivering out of hours care in this country."