OBJECTIVES:  In Norway, disease severity is one of three criteria for allocating scarce resources in the health care sector. Severity is weighed against cost-effectiveness, making willingness-to-pay an increasing function of severity. Despite a consensus that severity should influence priorities, how to define and measure severity remains unclear. A recent white paper on priorities in health care suggested measuring severity as loss of future “good life years” (QALYs). This research explored the Norwegian population’s allocation preferences using three definitions of severity: absolute shortfall (AS, loss of future QALYs), proportional shortfall (PS, AS relative to expected remaining QALYs if disease-free) and fair-innings argument (FIA, previous and future QALY loss). METHODS:  A random sample of 1,342 Norwegians aged 18 and above, answered a web-based survey. Respondents were randomized to one of four survey versions, each consisting of seven priority tasks. For each task, respondents chose between two patient groups that varied in (1) age at disease onset, (2) remaining life years without treatment, (3) prospective health-related quality of life (HRQoL) and (4) previous HRQoL. We assumed identical treatment effectiveness between patient groups. We analyzed the data using multiple logistic regression. RESULTS:  Respondents' allocation choices were more responsive to changes in AS than PS. A one-year increase in the difference in AS between patient groups increased the odds ratio for prioritizing the most disadvantaged group by 4% to 6% (p<0.001). Similarly, a one-year increase in retrospective HRQoL loss resulted in an odds ratio for prioritizing the disadvantaged group of between 3.1 and 5.7 (p<0.001). CONCLUSIONS:  Respondents seemed more responsive to absolute shortfall than proportional shortfall. Combined with preferences in favor of considering previously lost HRQoL, this suggests fair-innings argument may be the preferred measure of severity among the Norwegian population when allocating resources in the health care sector.