The aim of the diploma thesis was to study factors influencing behavior of dogs in public spaces in Brno. 133 pairs of dogs were observed. The dog's gender, dog age, and age of the dog owner affected the interaction. The owner of the dog affected by the interaction. The dog's sex, dog age, and dog age influenced sniffing. All factors that were monitored influenced the play. The gender of the dog affected the marking behavior. The gender of the dog owner affected the threat. The dog's owner's gender affected bite occurrence.