Considerations beyond cost-effectiveness are important in reimbursement decision making. We assessed the importance of disease severity in drug reimbursement decision making in Belgium, France, The Netherlands and Sweden. We investigated scientific literature and policy documents and conducted three interviews in each country (four in The Netherlands) with persons involved in drug reimbursement. Disease severity is an important consideration, especially where the level is high. The Netherlands operationalizes disease severity using the proportional shortfall approach. Sweden uses categories to give an indication of the level of severity. In The Netherlands and Sweden, severity only implicitly plays a role in the decision whether to reimburse a drug, whereas in Belgium and France it also explicitly plays a role in determining the willingness to use public resources. Interviewees acknowledged that as well as a qualitative description of the disease, quantitative information may also be useful as input for decision making. None of them, however, considered this to be of decisive importance. Although disease severity is important in drug reimbursement decision making in all four countries, all seem to struggle in explicitly specifying its actual role. Belgium and France are the most explicit by using levels of severity in setting reimbursement levels; all four countries could, however, improve the transparency of its actual importance relative to the other criteria in the decision-making process.