Background: Healthcare systems face the problem of insufficient resources to meet the needs of ageing populations and increasing demands for access to new treatments. It is unclear whether doctors and consumers agree on the main challenges to health system sustainability. Methodology: We conducted a mail survey of Australian doctors (specialists and general practitioners) and a computer assisted telephone interview (CATI) of consumers to determine their views on contributors to increasing health care costs, rationing of services and involvement in health resource allocation decisions. Differences in responses are reported as odds ratios (OR) and 99% confidence intervals (CI). Results: Of 2948 doctors, 1139 (38.6%) responded; 533 of 826 consumers responded (64.5% response). Doctors were more concerned than consumers with the effects of an ageing population (OR 3.0; 99% CI 1.7, 5.4), and costs of new drugs and technologies (OR 5.1; CI 3.3, 8.0), but less likely to consider pharmaceutical promotional activities as a cost driver (OR 0.29, CI 0.22, 0.39). Doctors were more likely than consumers to view 'community demand' for new technologies as a major cost driver, (OR 1.6; 1.2, 2.2), but less likely to attribute increased costs to patients failing to take responsibility for their own health (OR 0.35; 0.24, 0.49). Like doctors, the majority of consumers saw a need for public consultation in decisions about funding for new treatments. Conclusions: Australian doctors and consumers hold different views on the sustainability of the healthcare system, and a number of key issues relating to costs, cost drivers, roles and responsibilities. Doctors recognise their dual responsibility to patients and society, see an important role for physicians in influencing resource allocation, and acknowledge their lack of skills in assessing treatments of marginal value. Consumers recognise cost pressures on the health system, but express willingness to be involved in health care decision making.