Person-environment fit refers to the quality of the relationship between the person and the environment. A way to operationalize this relationship is to evaluate environment quality perception (Horelli, 2006). In hospitals, physical environment is not simply a backdrop for the delivery of healthcare (Harris et al., 2002) since research has shown that healthcare physical environment attributes affect users’ satisfaction and well-being (e.g., Leather et al., 2003; Becker & Douglass, 2006). The general aim of this PhD project is develop a theoretical model in which this relationship is mediated by environmental quality perception. Specifically, this research project pretends to: a) adapt and validate a measure for assessing patients, visitors and staff perceptions of hospital environmental quality, b) explore the relationship between environmental attributes, users’ environmental quality perception and well-being, c) identify the physical environmental attributes that impact the most on hospital quality environment perception of different kinds of users, with different needs; and d) test, in laboratory and field settings, the impact of modifications in hospital environment (alternative design solutions) on users’ hospital environmental quality perception and well-being. The aim of the first study described here is to validate a measure on the perception that patients, visitors/companions and staff have about the quality of hospital environment (Perceived Hospital Environment Quality Indicators (PHEQI); Fornara, Bonaiuto & Bonnes, 2006). PHEQI contains four indicator scales on perceived hospital environment quality, three evaluating different physical environments and one evaluating a social environment: (a) spatial–physical aspects of proximal external spaces of the hospital (16 items); (b) spatial–physical aspects of the care unit (21 items); (c) spatial–physical aspects of the in-patient area and of the out-patient waiting area (18 items); (d) social– functional aspects of the care unit (16 items). Statistical analysis revealed a total of 12 PHEQI factors of quality environment perception. In a recent version of the instrument authors present only three perceived hospital environment quality indicator scales. These scales were translated from Italian to Portuguese, using the translation and back-translation method, and pre-tested. The scales were then completed by users using one in-patient area and one out-patient area of four hospital’s orthopaedic units with different spatial and physical conditions, in Lisbon. Also these four orthopaedic units were described and evaluated with respect to various design attributes that cover the same issues as the PHEQI scales concerning spatial-physical aspects. This evaluation was done by two independent judges with a theoretical background in architectural design issues. The first objective is to explore factorial structures of the scales for Portuguese population and test for convergent and discriminant construct validity and criterion validity. This will allow to verify how design and socio-functional attributes are organized (more or less connected, more or less distinct) in users’ cognitions. Second objective is to develop a shorter version of PHEQI. This version can be useful tool in future studies and also in post-occupancy evaluations. Third objective is to make use of the cumulative risk model methodology to analyse the features and specific elements of the physical environment of healthcare facilities that significantly contribute for the perception of patients, visitors/companions and staff about hospital environmental quality. At the present stage we are collecting data. To discuss it will let us prepare future studies.