The importance of nutrition is at the very core of the existence of the human race, regarding multiple aspects - from the health aspect, through the preservation of the well-being of the individual to the hedonistic aspect of enjoying food. As food expenses are one of the largest individual household expenses, when planning an individual's diet, there is also a strong economic component that is relevant when making purchasing decisions. There are numerous definitions of functional food present in the scientific literature that try to determine its meaning as precisely as possible - it is considered that food can be characterized as "functional" if, in addition to its basic nutritional values, it positively affects the health of the individual, reducing the risk of developing certain diseases and increasing the well-being of the organism. The functional food market is increasingly developed, and consumers today tend to think about what they eat much more than in the past, which is why the concept of functional food products has increasingly attracted scientists, manufacturers, and consumers. Research on functional food from the aspect of consumer behavior in Croatia is relatively scarce. According to some research results, Croatian consumers are insufficiently educated and informed about the concept of functional food products and the health benefits of these products. This very fact was the main motivation for this thesis with a desire to provide a deeper insight into the factors of consumer behavior regarding the segment of functional food. The research carried out as part of this thesis is based on the theory of planned behavior, which is considered very suitable in social research, and particularly suitable for analyzing the influence of various factors on consumer behavior. The basic model, which includes the influence of attitudes, subjective norm and perceived behavioral control of respondents on the intention to purchase functional products, is expanded by the individual health concern segment. Empirical research was conducted on a convenient sample of 154 respondents and a significant influence of attitudes, subjective norms and concern for individual health on the intention to purchase functional food was determined by linear regression. The scope for future research is reflected in the research on the impact of the socio-demographic characteristics of respondents on the intention to purchase functional products, and the work itself, apart from the scientific one, also contains a practical component for all sections of the interested public who consider the implications of this research relevant - from the consumers themselves, through the media and representatives of the food industry.