The theory of demographic transition, with a long precedence, is one of the sustainable conceptual frameworks which are used to explain the historical and social evolution of populations. During the process of mortality transition, the causes of death are changed from infectious and parasitic to non-infectious diseases. The concomitant epidemiological transition, oversees the overall and complex patterns of health and illness and tries to explain the interrelations between social, economic, biological and demographic factors affecting such patterns and the ensuing consequences of these changes. Using existing data, this article investigates the patterns of mortality and epidemiological transitions in Iran for the last decade. While historical data indicates that mortality transition might have started from 1320 in Iran, examination of changes in trends of causes of death, during 1375-1384, indicates that the mortality rates caused by infectious diseases have declined 50%. It also shows a considerable increase in rate of four major causes of death that is, heart disease, cancer, lung disease and unintentional injuries (accidents). Taking it together, the rate for these leading causes of death has jumped from 39.4% to 63.1%, suggesting that Iran is experiencing a continuous epidemiological transition.