One of the first things women would bring on a desert island is cosmetic. All women have a special relationship with their cosmetics. Cosmetics have an essential role for the wellness of women of the twenty first century, who are actives and independents. The purpose of this article is to precisely describe and understand the link between woman and their cosmetics, and investigates on the influence of brand loyalty on cosmetic buying behaviour of female consumers in France, country of fashion and refinement. Different notions are described: brand loyalty, trust, gender role, age class and advertising. These different subjects bring a concrete vision of what researchers already found to explain the research question. A questionnaire was sent to hairdresser salon female clients and 122 of them send the questionnaire back. Individual interviews were also done to extend the trends found with the survey. The research results showed that there is a strong link between factors such as trust, satisfaction and service quality with cosmetics brand loyalty.