In this article, a multi-criteria approach is proposed to prioritize user-stories in an Agile Software Development environment. User-stories are characterized by their interdependencies and the effort of development. The PROMETHEE II multi-criteria method is proposed as a technique to find a ranking of user-stories, but it needs information about preference thresholds and criteria weights. These parameters are considered stochastic variables and a simulation process is performed to explore robustness of the user-stories prioritization. We show that the information provided by the approach reveals zones of ambiguity in which some user-stories cannot be ranked. An example illustrates this approach and its utility is analyzed. Limitations of the approach are discussed and future research is proposed.