No site has been chosen, but a statement from Sainsbury's said: 'We have responded positively to the government's interest in GP surgeries and we are committed to working on delivering at least one in-store GP surgery.
We are looking for sites.
'Customers will benefit from the accessibility of our stores.'
It follows the recent health White Paper's push on opening up competition among the private and voluntary sectors in primary care in deprived areas.
A Sainsbury's spokesman said it was unclear whether it would use an alternative provider medical services contract.
Dr Christopher Rossall, who runs a practice in Preston, Lancashire, on the same site as a Sainsbury's supermarket with a pharmacy, is concerned about the potential competition.
'I think five years ago it would not have been able to compete with the 24-hour service GPs offered,' he said.
'But we've given up a lot of time at evenings and weekends now so there's a chance patients might change if they could.'
He said it would be impossible for a small practice to compete with a financially strong company like Sainsbury's.
'If it were to open a practice in direct competition with us, I would have to think about becoming salaried by it,' he said.
He added that a lot of Sainsbury's shoppers tended to be from higher social groups, so questioned whether the plan would help deprived patients.
A DoH spokesman said: 'We need to extend access to GP services, and the inclusion of supermarkets is one of the ways which this can be achieved.'
Tesco has denied similar plans.