In order to be able to evaluate beforehand the impact of a strategical or tactical move, decision makers need reliable previsional systems. What-if analysis satisfies this need by enabling users to simulate and inspect the behavior of a complex system under some given hypotheses, called scenarios. Though a few commercial tools are capable of performing forecasting and what-if analysis, and some papers describe relevant applications in different fields, no attempt has been made so far to comprehensively address methodological and modeling issues in this field. This paper is a preliminary work in the direction of devising a structured approach to designing what-if applications in the BI context. Its goal is to summarize the main lessons we have learnt by facing real what-if projects, and to discuss the related research issues. We also provide a methodological framework for design and discuss its application to a case study. Categories and Subject Descriptors H.4.2 [Information Syste...