© GATA.Background: Society’s lack of knowledge about organ donation and insensitivity to this issue emerge as one of the low organ transplantation reasons. The aims of this study were to determine the middle school and high school students’ level of knowledge about organ, tissue and blood donation-transfusion, to provide knowledge to the students about the subject and also to evaluate the effectiveness of this informative work. Methods: The study group consisted of 342 high school students. Created questionnaire included 40 questions of knowledge regarding organ and tissue transplantation and blood donation. Knowledge level of the students was measured by the questionnaire. After a week of this process, an informative education study that lasted about 40 minutes was performed to all students including the studying group by the researchers regarding organ and tissue transplantation and blood donation. Fifteen days after the informative education, the same students in the same classes filled in the same questionnaires previously applied. Results: Organ and tissue transplantation and blood donation knowledge levels of those who obtained 15 and over scores as a result of the ROC Analysis were considered to be adequate. The knowledge average score was 17.81±7.99. The item “description of transplant” was the most correctly known knowledge question. The knowledge average score students obtained from tissue, organ and blood transfusion-donation items by before informative study was lower than after informative study. Conclusion: Informative activities to the students were found to be effective in increasing the students’ level of know ledge about the donations.