Background: Functional food is a key element in the prevention and treatment of many diseases. The ingredients it contains, such as phytosterols that lower cholesterol, also have a preventive effect on type 2 diabetes, atherosclerosis and heart attack. Phenolic compounds have antioxidant, anti-inflammatory and antiviral properties. Xylo-oligosaccharides control insulin levels, and fibre lowers blood pressure, potentially reducing insulin resistance. These beneficial properties mean that there is an increasing interest in this kind of food. Objective: The aim of the study was to assess the state of knowledge and behaviour regarding functional food among adults and to answer the question whether there are differences between the state of knowledge and behaviour of women and men. Material and Methods: The survey was conducted among 301 people, including 181 women and 120 men. The research tool was an original survey questionnaire. Results: The definition of functional food is known to 42.5% of people (47.5% of women and 35% of men), while the definition of prebiotic is known to 41.9% of people (43.1% of women and 40.0% of men). For 56.2% of respondents, the factor encouraging the consumption of functional food was a healthy lifestyle, and for 54.7% of them, the product composition was the main purchase criterion. Among functional products, cereals or muesli were most often consumed for breakfast by 35% of men and 55.8% of women, 42.5% of men and 33.7% of women were eaten oils for lunch. For dinner they most often consumed fruit teas, herbal teas, herbal mixtures, this answer was given by 25.8% of men and 29.8% of women. Conclusions: Knowledge of functional foods is unsatisfactory, and no differences in the knowledge of women and men have been observed. Consumption of functional food is generally low, and no differences in consumption have been observed between women and men.