Smoking is one of the major public health challenges due to the harmful substances in tobacco smoke, including nicotine, which has carcinogenic effects. Many people are seeking healthier alternatives to smoking, with e-cigarettes becoming popular. Although they contain nicotine, e-cigarettes are often considered a more acceptable option. Research on the long-term effects and true harm of e-cigarettes is still inconclusive due to their novelty on the market. There is a need for better labeling and categorization of e-cigarettes, which the new Tobacco Products Directive aims to regulate. The use of e-cigarettes is increasing, especially among young people, and could become the new addiction of the 21st century. The aim of this thesis was to investigate the factors influencing user loyalty towards e-cigarette brands. The research was conducted on 120 respondents using a survey questionnaire. The factors examined to determine their impact on loyalty included brand recognition, price, satisfaction, loyalty, and effectiveness for different e-cigarette brands. The e-cigarette brands for which loyalty factors were assessed are Wiip, Elf Bar, HIGS, Vaporesso, and IZY Vape. The research results showed that satisfaction is the factor that most influences customer loyalty when choosing an e-cigarette brand. Other factors have a lesser impact on user loyalty towards a particular e-cigarette brand. To maintain their market position, competitive brands should focus more on factors such as price and effectiveness to further strengthen user loyalty.