Intellectual protection in fashion industry issues constitutes an important and difficult aspect of fashion law – the innovative law specialization which is an amalgam of different branches of law. The objective of the article is to analyze the registrability of color per se trademark in fashion sector. The incentive that dedicate the paper to these matters was the proceeding in a case Christian Louboutin v. Yves Saint Laurent based on US law and concerning the infringement of the red sole trademark. For this reason the article focuses on US law and presents regulations contained in federal legislation, Lanham Act in particular, as well as USPTO practice in such cases and appropriate judicature. The analysis covers trademark as a legal concept, judicature’s standpoint towards the nature of both color per se trademark and colors trademark in fashion sector, last but not least – legal problems that arose in Louboutin v. YSL case. The article is summarized by a synthesis of the courts’ opinions and brief conclusions concerning trademark protection of color per se in the fashion industry.