The growing importance of the concept of sustainability makes brands and consumers more aware, and their attitudes are consequently reflected in their behavior. The need to change consciousness is prompted by growing environmental problems. The concept of sustainability has especially found its application in the fashion industry because fashion industry plays a big role in environmental pollution, which is the topic of this paper. This paper offers a theoretical basis for defining the concept of sustainability, explaining the concepts of fast and slow fashion and the necessity of developing other concepts related to sustainability in the fashion industry, as well as a series of previously conducted research that puts members of generation Z in interaction with the mentioned concepts. The research seeks to reveal the attitudes of generation Z towards sustainability in the fashion industry and to reveal what influence these attitudes have on their behavior, i.e. making a purchase decision. This paper also determines what encourages or prevents members of the mentioned generation from purchasing fashion products with sustainability features. The research was conducted on people born between 1995 and 2010 through a survey of 19 questions via a Google form. It was discovered that the generation in the focus of the research values sustainability when making a decision to purchase fashion products, but puts other factors before sustainability, such as comfort, quality and prices. Despite the presence of environmental awareness, sustainable behavior is absent, thus creating a gap between attitude and behavior. They justify their lack of sustainable behavior, to the greatest extent, by the high price of the product, despite the fact that research has confirmed their willingness to pay a higher price for a fashion product with sustainability features.