BACKGROUND: Medical professionals' knowledge of and attitudes toward organ donation and transplantation have positive impact on donation rates. The aim of this study was to determine the knowledge and attitude of medical university students in Iran about organ donation and transplantation.METHODS: This cross-sectional study was carried out on 1078 undergraduate students in Golestan University of Medical Sciences, Gorgan, Iran, from January to June 2019. All eligible students were recruited using convenient sampling. Data were gathered using knowledge and attitude toward organ donation and transplantation questionnaire. The higher scores of both subscales, the knowledge subscale (range from 0 to 13) and the attitude subscale (range from 13 to 65), indicate the better knowledge and attitude toward organ donation and transplantation.RESULTS: The mean age of students was 22.24±5.16 years. Finding showed that the mean score of students' knowledge and attitude toward organ donation and organ transplantation were 8.48±1.71 and 48.55±8.11 respectively. Also, the mean score of students’ knowledges in females (P<0.001), married (P=0.001) and who had organ donation card (P<0.001) was significantly higher. Nearly all of the students had heard about organ donation (98.3%) and organ transplantation (98.4%). Majority of them pointed that their source of information about organ donation and transplantation was television (TV) program (47.1%). Most of the students (73.8%) reported that they agree to donate their organs but most of them (67.5%) did not know how to obtain organ donation card and only 9.6% of them had the organ donor card as a volunteer donor.CONCLUSION: According to finding, despite the awareness and favorable attitude about organ donation and transplantation among medical students, the number of registered donors was low. In addition to promoting college students’ awareness about organ donation for increasing registered donors, it is needed to aware and pursue lay people through social media.