Evidence Based Design (EBD) is a scientific analysis methodology that emphasises the use of data acquired in order to influence the design process in hospitals. It measures the physical and psychological effects of the built environment on its users. EBD uses formularization of hypothesis, testing/analyzing and outcome gathering as a framework. The design practice, in general, has always been based on a combination of legal, technical/ functional/ and aesthetical knowledge. This generalization has been shifted to another level after the implementation of EBD. In the last 30 years many case studies were collected which demonstrate the built environment's impact on users. EBD methodology can be applied to any type of building, but it is particularly used to analyze the efficiency of healthcare facilities. The Goal of this paper is to demonstrate various applications of EBD principles in healthcare buildings through case studies concerning: - reduction of infections - reduction of stress on medical staff - improved patient healing In addition to the analysis of case studies, we will also focus on official EBD researches developed by healthcare designers and professionals as "alternative solutions". These alternative "ad hoc" solutions are developed in order to answer EBD research results. The solutions that are developed from the results can answer the real needs of each hospital and improve best technological practice to reduce infection, stress and improve patient comfort. Abroad the EBD research results are studied and used by many contemporary hospital architects to develop new solutions to meet the specific requirements of any hospital project they are currently designing. This procedure demonstrates that for each outcome and key finding, there is always at least one alternative solution and, therefore, the achievement of a new hypothesis, case studies to test/measure and outcome to gather occurs. This repetitive attitude leads to a "virtuous circle" where the development of new samples produces a double- positive effect in both EBD research (in terms of new case studies to analyze) and in EBD lessons for implementation in various hospitals. Through this paper the authors state that the combined effort is needed by EBD practitioners, healthcare architects and hospital managers for the improvement and diffusion of EBD in healthcare, especially in Italy where this methodology is not widely used.