The onset of the fourth stage of the epidemiological transition in Iran coincides with a surprise, i.e., unintentional accidents and transport accidents alternately stand in the second and sometimes the third place regarding the causes of death. The case is not only due to its effect on the level and pattern of mortality, a population issue exponent, but also its socioeconomic consequences always present a range of social issues for researchers and planners. The main question in this article is: how much is the demographic burden of mortality resulting from unintentional accidents? To answer this question, data from the death record in the health record system has been used. The results show that unintentional accidents as the cause of death for men are in second place after cardiovascular diseases, and are in third place for women after cardiovascular diseases and neoplasms. Also, 72.5% and 62.1% of unintentional accidents for men and women, respectively, are transport accidents. The findings based on the life table show estimations of about 70.5 and 72.8 years for life expectancy at birth, respectively, for men and women. In general, unintentional accidents reduce 2.7 years of life expectancy for men and 1.1 years of women's life expectancy, of which the amount of, respectively, 1.9 and 0.7 years belong to transport accidents.