The logic of youth fashion is based on the rejection of Fashion itself. Whether for Benetton, Kookdi, Autour du morule, Chevignon or Naf-Naf... those brands have built themselves, unlike Chanel, St Laurent or Lacroix, a mold-breaking personality which doesn't owe anything to the past, nor to an original stylist or a creative artist... Their success is mainly the result of their communication, which doesn't content itself with the production of a brand image, but endows it with a genuine discourse. The discourse which goes beyond the traditional fashion discourse area, to be in line with the current expectations of youth. Semiology, the study of the signs and their links, is an essential tool to analyze, build and master, these new forms of youth fashion communication. Associated with conclusions of sociology and aesthetics, this peculiar approach allows us to set the problem as follows: the most interesting part of youth fashion communication consists in its different ways of opposition against classical fashion which leads to defining it as an anti fashion. The success of youth communication is above all linked to this skill of setting back youth fashion against the universe of fashion especially now when youth has become the cardinal value of fashion ( versus statutory elegance and pattern elitism ) and when generation gaps are reduced. The challenge of youth communication is the authenticity of the breaking point between the fashion system and youth fashion, bearing in mind that youth communication must be paradoxical. This new paradoxical fashion can be defined by its capacity to get out of the fashion through a discourse which is independent from the clothes themselves, i.e a fashion of the anti-fashion which rejects a fashion of the appearance to stress the importance of the genuineness of a real way of being. A semiological approach allows to decipher these shifts of trends, to define the codes and the expression modes and above all to master the consistency of the sign systems created according to the targeted commercial and marketing development of the trademark.