Introduction: When we speak about food safety, we must have in mind that the process of improvement is more than only the science on nutrition. The behavior of people is what matters the most. To improve the assurance of food safety, we have to realize that, in the process, we need knowledge of not only the science on nutrition but also behavioral science. Purpose: The purpose of the master’s thesis is multifaceted. First, we acquired and analyzed the scientific publications according to the keywords and phrases in the field of food safety assurance among food handlers. By means of semi-structured interviews, we then gained the in-depth insight into the implicit perceptions of the food handlers and their opinions regarding the obstacles in assuring the food safety in catering establishments. Methods: Combined methodological approach embraced the quantitative part which represents a systematic review of the literature where we analyzed 37 scientific publications which focus on the knowledge, attitude, behavior, and food handling practice of food handlers. Then, we analyzed scientific publications (systematic text analysis) and semi-structured interviews to ascertain attitude and practice of food handlers. Results: We presented the summary of scientific publications (N= 37) in the tables with regards to the used model, methodological approach, research method, the number of respondents, ascertainments in the field of research, and inclusion of the research goals (knowledge, attitude, behavior, and food handling). The combined methodological approach is used only in 9 studies (24.3 %). The quantitative approach is used in 22 scientific publications (59.5 %). The qualitative approach is used in 6 scientific publications (16.2 %). We performed semi-structured interviews with ten food handlers where we ascertained that knowledge of food handlers is insufficient and influences handling food. In spite of training of employees, inappropriate handling food still occurs, which means that the knowledge transfer into practice is insufficient or even incorrect. Discussion and conclusion: We discovered the deficiencies in qualifications and knowledge of food handlers, examined the methodological approaches of scientific publications on research goals. We recommend a new concept of food handlers training to be prepared on the level of the competent ministry in cooperation with the professional services in the field of food hygiene.