The aim of this paper is to present the fashion system as a “cluster” and to evaluate the characteristics of Product Lifecycle Management considering various factors, especially the different approaches in dealing the market needs. In particular, the “ready-to-wear fashion” and the “fast fashion” models will be presented and compared. The paper, takes the Italian fashion system as the unit of analysis and it also assumes that consumer behavioral factors act in a non predictable way (randomly) under the constantly changing social and cultural environment. Considering the inner complexity of a whole market system, a simplified System Dynamics modeling is proposed.