Organ shortage is the most limiting factor for transplantation systems. The total value of life lost due to death because of waiting for an organ transplant is greater than $ billions in the world and the excess demand for organs has been increasing over time. We report here the impact of Ramadan on willingness to organ donation in Iran.In a retrospective cohort, we analysed the trend of registries for organ donation in a single center in Iran. Data was extracted from organ procurement unit of Masih Daneshvari hospital. Monthly donation willingness registries achieved to 11528 participants during Ramadan 2007, this rate was 4538 in previous month. The increasing rate was 154 percent. There was a significant difference by means of sociodemographic data of those registered in this month in comparison to the previous months. Influence of Ramadan on donation willingness is similar to its promotive effect of religious behaviors. Donation of an organ is encouraged by Islam, as according to this religion, saving a life is saving all people. This effect may be secondary to the realize of the reality of death or making people to think to other people.