The interest in amateur running (including long-distance runs) has been growing in a dynamic way for several years. It is reflected in a significant increase in the number of sports events including marathons and half marathons. The paper describes research aiming to estimate risk of organizing running events in Poland. The presented results refer to half marathons organized in 2018. Professional risk management is a starting point of realizing objectives set by organizers, including assuring safety and satisfaction of all interested parties. The conducted research (both preparatory and proper) has allowed for the identification of risk factors and estimating risk by the representatives of the runs’ organizers. The identification was realized by 8 experts (the Delphi method), whereas there were 24 representatives of 11 half marathons in Poland engaged in the risk estimation. The latter was based on the average (of impact and probability). The present article does not present the results of the factor analysis and focuses, which complemented the result of risk estimation. The research results provide concrete information about the priorities on which event organizers may focus in order to mitigate risk. The results also amount to the basis of in-depth risk estimation and analysis for examining trends and the efficiency of undertaken mitigation actions.