Nowdays, service quality is of a great importance for the success of every company. Nowadays, quality is of a great importance for the success of every company. It is evident that different experts have different opinions about the impact of service and product quality on customer loyalty. Restaurants are the main part of the hospitality industry and are of great importance for the tourism sector. In the Republic of Croatia tourism affects economic development, as well as the standard of life quality of the resident population. The aim of this graduation thesis is to analyse the quality of services and products and their influence on the loyalty and perception of users on example of an Croatian company Submarine. Submarine is a Croatian fast food chain that has branches all over Croatia, but also abroad. This thesis contains an survey questionnaire containing 2 questions with socio- demographic data,22 questions divided into 5 dimensions and 3 loyalty questions. 312 respondents, who were randomly selected from the area of Rijeka and Zagreb, participated in the research. The research was carried out in the field directly by researcher herself and via QR code. The ultimate purpose of the work was to determine the company's quality level and to find areas that could be improved. The results of this research showed that the best rated dimensions were: responsiveness and reliability. Also, the applied contribution of the work is visible in the form of guidelines for improving the quality of services and loyalty. Key