The aim of this study is to evaluate the signifi cance of externalities in order to ensure food security. Particular attention has been paid to environmental services, which are often unnoticed in agricultural production processes. The study is theoretical in nature. The analysis was based on the available literature on food security, environmental services, and the theory of externalities. The results indicate that externalities aff ect food security. This concerns all four pillars of food security: food availability, food access, food utilization, and stability of supply and access over time. Furthermore, the relationship includes both, the positive externalities provided by the environment and used by agriculture and households, as well as the negative externalities resulting from agricultural production, which adversely aff ect the environment.