Objectives: Health Technology Assessment process is generally suitable in uncertain decision environments to support decision makers for reaching the optimal solution to HTA problems. This paper has investigated the state-of-the-art methods utilized in appraisal process, establishing how differences in assessment methods may affect the efficiency of appraisal process. Methods: PubMed, CINAHL, Cochrane Database, EMBASE, Scopus, Web of Science electronic databses and grey literature were searched to explore and compare the use of HTA focusing on its impact on health care decisions. Papers were included up to May 25, 2016. The reviewer has screened titles and abstracts and extracted data from eligible full-text articles and handbooks. Results: There are wide differences in the assessment methods that influences the appraisal process. These differences, in part, are the result of (i) the selection criteria (identified by each organization) for the technology assessment; (ii) the possibility to establish the priorities related to the performance of the alternative technologies as well as to synthetize the results into a structured output. Among the found methods, the Multi Criteria Decision Analysis techniques rely on preference capturing, statistical analysis, and synthesizing data. The authors have also identified additional assessment methods (AdHopHTA toolkit, mini-HTA, EUnetHTA Core Model) that consist in a practical guidance for assessing health technologies, but they do not foresee the priority analysis, data aggregation and well-defined and structured outputs. Conclusions: An overview of the assessment methods utilised in appraisal process is provided, by outlining the main strengths and weaknesses. Results show that the impact of such methods on the efficacy of appraisal process can therefore differ considerably due to methods of investigation and analysis adopted. The authors suggest that the MCDA techniques can be tailored to any appraisal, providing a reliable, transparent and transferable data about selected technologies that can be easily taken up into decision-making process.