Presented contribution deals with the problem of impacts of brownfields on prices of surrounding real estates, thus, the aim of the paper is to investigate how and why unused sites and buildings reduce prices of real estates located in the proximity of brownfields. This assumption has been surveyed and confirmed by secondary, but also primary research. As the case study, an area of the statutory city of Karvina has been selected due to the occurrence of plenty of brownfields. Respondents of the survey also expressed their opinions and attitudes about factors and characteristics of brownfields that are of key importance from the point of view their negative impact on the prices of real estates. Primary research has been conducted by means of the questionnaire survey in the second half of 2016, secondary research, which has been done in 2016 and 2017, has been based on analysis of real estate prices located in the proximity of selected brownfield Kovona. The analysis of local real estate prices covered the period of one year. It was found that proximity of brownfields might reduce usual prices of real estates by more than 20 %. Phenomena that are connected to the occurrence of brownfields include a concentration of socio-pathological behaviour and risks connected to possible contamination of the site that threatens health of the population that lives in neighbouring houses.