The main purpose of this thesis is to analyze and introduce the competitiveness of Turkish clothing firms in the European market after Customs Union. In doing that, trends in European clothing were also emphasized. Furthermore, an industry analysis by using Porter’s framework (Porter, 1980) was also carried out. As a case study, Hasca Textile Industry Limited Company which is operating in domestic and European markets, is also introduced by making its competitiveness analysis and strategical planning with implementation proposals.