The poll of 1,000 GPs for the BBC programme Inside Out found that 56% of GPs expect to 'retire or leave general practice' before the age of 60.
The findings follow warnings from the RCGP that many parts of England need to increase GP numbers by more than 50% by 2020 to cope with rising demand on primary care.
The college also warned at its 2014 conference that 600 practices could close within a year because they were staffed by high numbers of GPs close to retirement age.
Responding to the BBC survey, GPC and BMA education, training and workforce committee chairman Dr Krishna Kasaraneni, who features in the Inside Out programme, said: 'The BMA has been warning for some time that there is a real and serious GP workforce crisis emerging across the country.
'GP services are under unprecedented workload pressure, with practices seeing record numbers of patients - 40m more annually than in 2008 – against a background of mounting bureaucracy and falling resources.
'This has led to a significant drop in GP morale, and, as the BBC’s survey shows, has led to a worrying number of senior GPs choosing to retire early or work abroad, at the same time that general practice faces a serious shortfall in the number of doctors choosing to train as GPs.'
Dr Kasaraneni said that in his own practice in Swinton, near Rotherham, two experienced GPs and a newly qualified one had moved abroad to work in the last year, citing pressure on the profession in the UK.
'Patients are already beginning to see the result of the increasing pressure on general practice in a decline in the number of available appointments, and losing highly experienced GPs will only exacerbate this crisis,' Dr Kasaraneni warned.
'We need politicians and policymakers to wake up to the severity of this problem. We need to address the huge pressures facing GP practices, guarantee that GPs are given the resources to be able to deliver the services that patients deserve and need, and work to ensure that general practice once again becomes an attractive career choice for the next generation of doctors.'