OBJECTIVES To our knowledge in most articles BIA is only defined as what it does. Some authors have tried to define it by comparing it to cost effectiveness analysis. But still there is no common stand-alone definition of the term Budget Impact Analysis available. Our aim is to provide such a definition. METHODS In the course of a PhD thesis we conducted a systematic literature review in order to identify methodological articles regarding budget impact analyses. We searched pudmed and seven other databases to identify relevant articles. From the eligible articles the different understandings and definitions of BIA were extracted and synthesized into a comprehensive definition. RESULTS Our search delivered 223 articles from which 28 met our inclusion criteria. 15 different approaches to describe BIAs were identified. Over the years (2001 to today) there was a constant improvement and increase of complexity in the descriptions. Nevertheless most of the late definitions are based on the work of Mauskopf et al. in 2005 and 2007. CONCLUSIONS Based on the results we suggest the following definition for BIA: “A budget impact analysis is a form of health economic evaluation. Its purpose is to predict the financial consequences of the introduction or removal of an intervention from the current healthcare setting. Therefore BIA is a framework to synthesize the best available evidence. Rather than calculating a precise impact number it provides a valid model to the decision maker, enabling him to understand the relative effects of his decisions. The analysis is undertaken by modeling two scenarios where the reference scenario is the status quo and the second scenario a simulation of the decision to be made. The model parameters are chosen according to the framework requirement of the decision maker.”