Four in ten family doctors plan on leaving the profession or retiring within the next five years.
GPs are blaming increasing workloads and declining morale with half admitting they have brought forward plans to walk away from the vocation.
Some 42 per cent of GPs polled said they intended to leave or retire within five years, up from less than a third (32 per cent) in 2014.
Meanwhile, almost a fifth (18 per cent) said they would leave or retire within the next two years.
The findings suggest the current GP crisis is set to worsen, making it even harder for patients to get appointments.
Researchers from University of Warwick questioned 929 GPs from the Wessex region about their experience of working in primary care.
Of the respondents, nearly 700 were aged between 35 and 64.
Nearly six in ten (59 per cent) said morale had worsened over the past two years, with workload a major issue.
Half of GPs said they were working longer hours than two years ago, while more than a quarter (27 per cent) said they had deliberately cut their hours.
Of those, 72 per cent said this was due to the intensity of their workload and 30 per cent put it down to stress and the effect on their mental health.
Health leaders have warned the GP crisis means one in six posts are currently unfilled, making it increasingly difficult for patients to see their family doctor.
Official figures show one in ten patients now face waits of at least three weeks to see someone at their local practice.
Despite the government vowing to create 5000 additional GP posts by 2020, recent figures suggest that a further shortfall of 1300 full-time GPs has developed.
Many are choosing go abroad for better lifestyles, while high numbers are a retiring early to avoid hefty taxes which kick in when their pension pot exceeds £1million.
Officials admitted last year that four in ten GPs were quitting the NHS within five years of finishing their training.
Meanwhile, recruitment drives for foreign doctors are struggling to keep pace with the rising demand.
In the latest survey, GPs suggested increased funding, more doctors, better education of the public and expanding non-clinical and support staff would all improve GP retention.
The researchers said that while some of these initiatives had been brought in, the effects were yet to be seen.
The poll further found that 41 per cent of GPs felt the increasing demands, expectations and complexity of patients was one of the greatest problems facing general practice.
This included people with more complex health problems, who were often older.
Lead author Professor Jeremy Dale, from Warwick Medical School, said findings all point to falling levels of job satisfaction among GPs.
He said: ‘Many GPs clearly feel that this is too little, too late and have failed to experience any benefit from these initiatives and are unable to sustain working in NHS general practice.
‘Intensity of workload and volume of workload were the two issues that were most closely linked to intentions to leave general practice, followed by too much time being spent on unimportant bureaucratic and administrative tasks.
‘There’s a worsening crisis in general practice. The situation is bad, it is getting worse and GPs are feeling increasingly overworked and increasingly negative about the future.’
Earlier this week, the Mail revealed how just one GP is having to cover night-time home visits covering a population of half a million in Shropshire.
Proposals in the NHS long-term plan including more funding and increasing the workforce are desperately needed, the authors say.
He added: ‘The point that came through repeatedly in the survey was that GPs felt that we’ve gone a long way down the road of insufficient investment and insufficient reward. Turning this around will be a mammoth task.’
Professor Helen Stokes-Lampard, chairwoman of the Royal College of GPs, said: ‘GPs are under intense strain – our workload has escalated in recent years, both in terms of volume and complexity, but we have fewer GPs than we did two years ago.
‘There is some great work ongoing to increase recruitment into general practice, and we now have more GPs in training than ever before, but when more family doctors are leaving the profession than entering it, we are fighting a losing battle.
‘The NHS long-term plan has aspirations that will be good for patients – but we will need the workforce to deliver it.’
Jonathan Ashworth MP, Labour’s Shadow Health and Social Care Secretary, said it highlighted the ongoing crisis within primary care.
He said: ‘Properly resourced General Practice is absolutely key to keeping people well and relieving wider pressures on the NHS, yet having spent time on the front line with GPs, it’s obvious morale is low – our GPs are overworked and under resourced with many experiencing burn out.
‘It’s time for a sustainable, fully resourced, funding solution for GPs and community care, along with credible measures to retain existing staff and recruit for the future. Ministers must act, otherwise patients will lose out once again.’