LCA is a decision support tool that evaluates the environmental impacts throughout the life cycle of a product or a process. This tool can also be used to assess the environmental performances of an integrated waste management system or to identify the one with the best performance through a comparative analysis of different scenarios. The result of the analysis depends primarily on how scenarios to compare are constructed, that depends on which fractions, and in what amounts, are sent to certain treatments/destinations. In the first part of the paper, we will introduce the concept of scenario, how it be can classified and how it can be built, as is clear from the literature. Then we will try to examine the criteria used in choosing the scenarios of waste management systems under the LCA, through a literature review. This critical review, which is the first phase of a larger study, highlights that arbitrary criteria are generally used in the selection of scenarios. In this way the best combination among all possible ones might not be considered; indeed, the best one among a discrete set of possibilities can just be identified. Furthermore, the paper highlights the advisability to identify an LCA-integrated tool that allows one to find the most environmentally-sound scenario among all those theoretically possible.