More than two in five people have no idea how to contact their GP out-of-hours service, a poll suggests.
A new survey found that 42% of people in England do not know how to contact a family doctor outside of working hours.
In recent weeks, poor out-of-hours services have been blamed for a rising tide of people turning up at A&E departments.
The new figures, released as part a national GP patients survey undertaken by NHS England, also showed that almost a third (31 per cent) of patients who used an out-of-hours service thought it took too long to receive care.
Health secretary Jeremy Hunt recently said that GPs should be ultimately responsible for out-of-hours care - even if they do not personally provide it.
Mr Hunt said there was a ”dramatic fall in confidence” in evening and weekend non-urgent cover since the last government changed the GP contract in 2004 to remove responsibility for out-of-hours care from family doctors.
The latest poll, conducted on almost a million people, appeared to show that practices were under pressure to cater for growing numbers of patients.
More than a quarter of those questioned said they had to sit in the waiting room for more than 15 minutes and 17 per cent said that their GP practice was not open at a convenient time for them.
Almost three-quarters said they would prefer if their local practice was open on a Saturday.
GP leaders said they were “trying our best with very limited resources”, saying that family doctors provided 90 per cent of NHS care with just 9 per cent of the budget.
Clare Gerada, chair of the Royal College of General Practitioners, said: “Our workload is ballooning and our patients are presenting with more complex and multiple conditions.
“We see over one million patients every day and we now routinely have well over 40 patient contacts per GP per day, sometimes going up to 60 and more - in the past this would have happened only in exceptional circumstances, such as a flu pandemic.”
She called for “urgent investment” in general practice.
David Geddes, head of primary care commissioning at NHS England, said: “General practice makes an enormous contribution to people’s health and well-being. Nine out of 10 contacts the public have with the NHS are with their GP practice.
“The GP patient survey highlights where patients are satisfied with the service they receive, but also helps us identify areas where we could do better and where NHS England along with CCG leaders need to focus. We will be looking at the results of this survey and working with our area teams to ensure issues that are important for our patients are addressed.
“Patients are at the heart of everything we do at NHS England and finding out how satisfied patients are with NHS services is key to this aim.
“The GP survey gives us insight into patient feedback on GP services in and out of hours and this will form an important part of our work to modernise and develop the contribution that general practice can make to the NHS going forward.”