The aim of this thesis was to evaluate differences in the quality of conventional and organic food. The primary focus was related to milk quality and perceiving changes in consumer behaviour. In order to achieve the objective was done an analysis of documents, compiled questionnaire survey and done research focused on the comparison of quality of organic and conventional milk. On the basis of analysis of documents organic food is evaluated like superior in quality, with higher nutritional value and lower levels of undesirable substances. Questionnaire survey showed that more than 50% of consumers do not buy organic food even though most consumers evaluates organic food as superior and healthier. The limiting factors are the high costs and poor availability. Research focused on organoleptic properties of organic and conventional milk confirmed the diversity of results. In the case of taste factor consumers prefer organic milk, but in the aspect of the smell they prefer conventional milk.