Undoubtedly, timely, continuous and reliable information on levels and trends in mortality and causes of death in populations is essential for priority setting for health programs.This research represents the first documented comprehensive attempt to estimate the leading causes of death and YLLs for Iran. While the completeness of the death registration system operated by the Iranian MOH&ME appears to be acceptable in the majority of provinces, further efforts are needed to improve the quality of data on mortality in Iran. A significant proportion of deaths in the Iranian MOH&ME's Death Registration System are being classified to cause groups that are of little relevance to either epidemiological research or health policy. Substantial changes to procedures for diagnosing causes of death are urgently required if the data are to effectively guide health policies and programs in Iran. This suggests that policies to reduce road traffic accidents, perinatal conditions (such as birth trauma and birth asphyxia) and major vascular diseases are urgently required in Iran.