This paper examines changes in children's concepts of health and illness following an action-oriented health education intervention in Bondo district of Western Kenya. The study is a feasibility study exploring a specific educational approach, and it combines elements of health education research and anthropological research. Forty primary schoolchildren aged 10-15 years of age underwent a 2-month intervention and were thereafter enrolled as health communicators in a longitudinal study for an additional period of 12 months. Data were collected before, during and after the intervention using in-depth interviews and the draw-and-write technique. Students' actions and their active participation were key elements in the intervention. Although the intervention from the beginning focused on two specific diseases (malaria and diarrhea), the students were involved in developing their own ideas and visions about which changes to make, which actions to carry out and which target groups to approach. Data showed that children had acquired new concepts of health, some of which incorporated elements of the old ones. More action-oriented health concepts were identified and a general change from an external locus of control towards an internal locus of control was found. The study concludes that students can modify and broaden their concepts of health and illness through action-oriented health education. Key factors are the development of students' ownership through active and participatory teaching and learning approaches. (Contains 4 figures and 2 tables.)