BACKGROUND: In tandem with fears about a GP workforce crisis, increasing attention is being focused on the supply and distribution of primary care services: on general practitioners in particular. Differential turnover and migration across health authority boundaries could lead to a maldistribution of GPs, yet comprehensive studies of GP turnover are non-existent. AIM: To quantify general practitioner (GP) turnover and migration in England from 1990 to 1994. METHOD: Yearly data from 1 October 1990 to 1 October 1994 were collected on GPs in England practising full time, including average yearly turnover, rates of entry to and exit from general practice, and net migration among GPs. All were calculated at the family health service authority (now the new health authorities) level. RESULTS: Average yearly GP turnover ranges from 2.9% in Shropshire to 7.8% in Kensington, Chelsea and Westminster; turnover is associated with deprivation and high-need areas. Migration of GPs across health authority borders was rare. Entry and exit rates were also positively related to measures of deprivation and need. Relatively underprovided health authorities lost 23 GPs over the study period as a result of migration; relatively overprovided ones gained three. CONCLUSION: Turnover is driven primarily by exits from general practice and is related to deprivation and high need. Retention appears to be the main problem in ensuring an adequate GP supply in relatively deprived and underprovided health authorities.