This study has been prepared as a preliminary study that will guide similar studies in the future. The aim of this study is to determine the effect of argumentation-based instruction on 6th grade students' knowledge and views about organ donation and transplantation. The study was conducted with 41 secondary school students in Turkey and a pre-test post-test single-group quasi-experimental design was used. Organ donation and transplantation was taught with argumentation-based activities for 2 weeks. The data was gathered by the open-ended questionnaire and content analysis was used in the analysis of the data. Before the application, it was observed that most of the students confused the basic concepts of organ donation and transplantation and they had some misconceptions. They also had incorrect information about the necessary conditions for organ donation and organs/tissues which can be successfully transplanted. After the application, it was observed that the misconceptions decreased significantly, and argumentation-based activities raised students' awareness and willingness to donate. These findings showed that argumentation-based instruction have had a positive effect on the students' knowledge and views about organ donation and transplantation.