BMA Scotland hopes its health hustings on Wednesday will be used to discuss what the NHS can and cannot afford as spending cuts take hold.
Dr Brian Keighley, chairman of BMA Scotland, said politicians 'need to recognise the reality of the choices facing NHS boards, and cannot afford to make unrealistic commitments to secure votes'.
'The range and level of services available now are more comprehensive and complex and patient expectations higher. To protect the principle of universal free healthcare, politicians must lead an open and honest debate with the public about what the NHS can and cannot deliver,' he said.
Financial watchdog Audit Scotland warned in December that with demand and costs continuing to rise and dwindling funding growth, the Scottish NHS faces financial pressures 'unprecedented' since devolution.
NHS Scotland plans to cut variation in GP referrals and move care into the community as part of a bid to generate £300 million in efficiency savings in 2011/12.
Scotland's health secretary Nicola Sturgeon has said she would like to see GPs become more involved in organising services but ruled out using competition or privatisation to deliver better care.