Environmental responsibility has been a widespread research theme. Its application in the health care sector however has been incipient. Given the fact that health care services tend to increase due to greater life expectancy and due to the fact that environmental externalities produced by human activity are having negative effect on human health, a deeper understanding of this relationship is appropriate. To contribute to this effort this thesis aims at investigating what are the main motivations driving hospital managers to adopt environmental responsibility programs and which actions that they have been implementing. A multiple case study was conducted involving four medically certified hospitals in Rio de Janeiro and São Paulo, selected out of different ownership types. Public, private and private HMO owned hospitals were selected for interviews and secondary data analysis. The research has shown that the main motivaitonal factors (competitive, ethical and regulatory) drive sustainability efforts of these hospitals and that the competitive and regulatory motivators have the potential to establishinga baseline of environmental performance which vary across ownership type (public or private). Further on the research has also indicated that the comprehensiveness of environmental actions does relate to the motivators that drive companies to adopt those actions. Two conceptual models are presented to illustrat these findings and offer bases for further research.