In some CCG areas in England, there are nearly 2,900 patients per fully-qualified, full-time equivalent (FTE) GP - while in others, the average number of patients per fully-qualified FTE GP is below 1,600.
The findings come as the overall number of patients registered with GP practices continues to rise rapidly, while GP numbers are falling.
BMA GP committee chair Dr Richard Vautrey said the large variation in patients per GPs between CCGs was 'a real concern'.
GP workload
GPs in Bradford City CCG manage more patients each than their counterparts anywhere else in England, GPonline analysis of figures published by NHS Digital shows. There are 2,886 patients per fully-qualified FTE GP in Bradford City CCG - more than a third above the median figure of 2,117 across all CCGs.
Meanwhile, in NHS Rushcliffe in Nottingham, there are just 1,577 patients per fully-qualified FTE GP - a figure lower than any other CCG in England.
Dr Vautrey said: 'It is a real concern - particularly if you are a patient in those areas where practices are struggling to recruit not just GPs but also other staff like nurses and practice managers - patients are losing out due to this long-standing recruitment and retention crisis we are going through.'
The GPC chair called for 'sustained investment' to boost GP numbers, encourage staff into underdoctored areas, and to help those areas become places that primary care staff felt were attractive to work in.
Health and social care secretary Matt Hancock said last week that he would look to set a new deadline for achieving the 5,000 FTE GP increase to the GP workforce promised by his predecesor Jeremy Hunt.
NHS England has suggested that digital-first GP services could be allowed to set up in underdoctored areas as a way to boost access to general practice in these areas.
