OBJECTIVES: : Hospital Based Health Technology Assessment (HB-HTA) became increasingly relevant because of its role in ensuring the introduction of evidence-based technologies and eventually in enhancing better outcomes for end-users. The organizational arrangements performed to run such activities are different and depend on several factors, even if some common points may be considered as minimal basis. The aim of this study is to identify and critically appraise existing different organizational models for HB-HTA. METHODS: Data used in this study was gathered within European Project AdHopHTA, granted under the 7th Framework Research Programme, which is aimed at strengthening the use and impact of HTA in hospital settings. A semi-structured interview was developed from the adaptation of the European Foundation for Quality Management Model, in order to inquire several aspects characterizing the organizational model. Finally, 7 HB-HTA units were involved in the study. RESULTS: Our results show that the organizational models depend on a number of contingent variables. Specifically, the combination of  the level of formalization/specialization and the degree of integration with the environment allows us to identify four ideal-types of HB-HTA units: the independent group, the integrated-specialized units, the standalone units and the integrated-essential units. CONCLUSIONS: Our results provide useful information on how different organizations face the challenges of HB-HTA. The findings and can be beneficial for policy-makers and professionals implementing HB-HTA and may give an overview on the next steps that the HB-HTA units could follow to further improve their current ways of working.