Abstract: Health organizations should be a reference in Corporate Social Responsibility and the encouragement of environmental sustainability, since the protection of the enironment implicitly involves the development of preventive measures in the field of health. Concern for the environment has typically been focused on manufacturing plants; however, health care organizations (HCO) are the only ones which generate all the classes of waste, with 20% of them dangerous due to their infectious, toxic or radioactive nature. Despite the extensive literature analysing environmental matters, there is no model to evaluate environmental sustainability in HCO's objectively. This contribution presents a Multi-Criteria Decision Analysis model which integrates the Fuzzy Analytic Hierarchy Process and utility theory to evaluate environmental sustainability in HCO's. The model uses criteria assessed by number of admissions and services provided annually; in this way the results can be compared over time within an organization and between different organizations, providing a tool for comparison or benchmarking between HCO's. The model has been applied to two HCO's of very different sizes.