Fear of being sued may make GPs reluctant to treat particular patients if hospitals are swamped with swine flu cases, according to the British Medical Association (BMA).
Says spokesman Dr Dean Marshall: "If someone has a heart attack we should send them to hospital, but during a pandemic, hospitals could be full and this may not be possible."
That might affect doctors' insurance cover, which requires them to send a patient to hospital in specific circumstances, such as a heart attack.
Meanwhile, because of the potentially deadly nature of the disease, doctors are also concerned about possible lack of death-in-service cover.
Dr Marshall told the BBC: "Doctors will be putting their lives on the line, and it is only right they can feel assured they are properly covered if anything goes wrong. Doctors are only human, and some will not want to go on the frontline."
Hospital doctors are covered by NHS indemnity insurance, meaning they are protected if sued over the care they provide.
But because GPs are effectively self-employed, they must make their own insurance arrangements, which may not cover them adequately during a serious flu pandemic.
Andrew Clapperton, from NHS Employers, said: "We are currently in discussion with both the BMA and the Department of Health to establish how we might best achieve this solution."