Medical devices are being developed continuously and their developers are under pressure to provide better evaluations of their products. Early assessment gathers the preliminary evidence to estimate clinical, financial, organizational, and social/ethical consequences of a particular technology. It seems a useful tool in predicting the potential of medical devices at the stage in which it can be adapted to fit the environment or the environment can be prepared for the technology. If the potential is low, further development can also be stopped. Although early assessment is recognized as an important part of medical device development process, there are many uncertainties in its nature and regarding the methods that are being used for its purpose. OBJECTIVE: To review different methods and their use in the early assessment of medical technologies. METHODS: An extensive systematic literature review of different early assessment methods. The authors systematically searched: computerised databases; published bibliographies of related topics; citations in articles reviewed; and references provided by colleagues. RESULTS: We identified 40 studies that met the inclusion criteria. 18 papers were either systematic literature Reviews (5) or theoretical papers (13). 10 papers were addressing specific applications of early assessment methodologies, and 12 papers were addressing theoretical concepts combined with examples. Those 22 articles were analysed and categorised with regard to the stage of  development of the technology, innovation type, perspective and aims of the analysis. Aims, outcome and uncertainties with regard to the outcome of the analysis were assessed. CONCLUSIONS: There is a need to clarify and communicate the aims and value of early assessment methods of medical devices to developers and policy makers, if early assessment methods are to become an integrated part of early activities in the development process.