BACKGROUND Organs from brain dead patients are the main source for transplantation. However, in most societies, including Iran, the family consent rate for organ donation is low necessitating improvements in public knowledge. Because teachers' knowledge has an important role to educate the next generations, this study assessed their knowledge and attitudes about brain death and organ donation. METHODS The present cross-sectional study included, 93 teachers selected from eight schools in Tehran, Iran, in 2009. We used a standardized questionnaire containing items which inquired about knowledge and attitudes of the participants regarding brain death and organ donation. RESULTS The mean age of the participants was 37 years and 48 (52%) were males. Eighty-seven (94%) of them had heard or read about organ donation, among whom 91% favored organ donation. The main sources of their information were television, radio, and newspapers. Sixty-five (70%) were willing to donate their own organs after death. Those with lower organ donation desire were in contact with a small number of patients who have chronic diseases, had less trust in organ donation networks and brain death diagnostic tools, expressed less desire to receive an organ, and had a low record of blood donation (P<0.05). CONCLUSION Our findings show that although most teachers had heard or read about brain death and organ donation, and approved of organ donation after death, a lack of exposure to patients with chronic diseases and a distrust of organ donation networks were greater among teachers with a lower desire to participate in this effort. Therefore, building trust in brain death diagnostic systems is necessary together with relevant educational programs.