Therapies used in the management of chronic diseases cause specific problems regarding reimbursement policy. Oxygen therapy is an example of such treatments that receive little attention from health care policy makers, due to their low cost to the health care budget and to their little importance from a social point of view. In this paper, we analyze the problems posed by this therapy in the Catalan health care system, as an example of the several aspects implied in the reimbursement of such kind of therapies. A technology assessment of this therapy was carried out showing that a change in the reimbursement of long-term home oxygen therapy (LTOT) was needed. Slow diffusion of new oxygen delivery modalities and over-prescription of LTOT were among the problems observed. The new system proposed is presented, and some preliminary results and consequences of the role of technology assessment in health care policy-making are discussed.