Though the significance of involving children in environmental sustainability efforts is widely acknowledged, we still lack evidence on what they think of environmental issues and about the protection of nature. The aim of the paper is to systematically describe the reasons that children give for protecting the environment. Thirty-three children (aged 6-11 years) participated in one of the six focus groups. Method of qualitative content analysis was used for analyzing the data. Study findings showed that participants were aware of some of the environmental problems or environmentally harmful behaviour like litter and pollution. Moreover, the study participants had various views about the importance of nature protection like maintaining clean environment, protecting human life and health, or protecting animals and plants. The reasons they gave for environmental protection were related to both humans and other parts of the nature. Furthermore, the participants learned about nature protection from sources like family, school, various literature sources, computer games, television and by watching how others behaved. Implications regarding results of the study are presented further in the paper.