Background: There are five different kinds of death; natural death due to any disease, accidental death, suicidal death, homicidal death, and undetermined death. Objectives: This study aimed to determine the major causes of death based on the autopsied reports to aid the development of preventive strategies. Methods: This study was a retrospective cross-sectional study consisting of autopsy reports of all suicidal, homicidal and occupational deaths recorded in all forensic medicine dissection halls in thirty-two provinces of Iran from March 2011 to March 2015. A questionnaire was designed containing all the information required for our studies such as gender, age, cause of death, and the autopsy reports. Results: There were 19288 suicides, 11655 homicides, and 8558 occupational deaths during five years. Among suicidal deaths, there were seventy percent male and thirty percent female. Most victims (about 22%) were between 18 to 24 years old (Mean age ± SD: 33.1 ± 13.1 years). The highest cases of suicide were 52% hanging, and 25% poisoning, respectively. Among homicidal victims, there were 18% males and 20% females. Most victims were between 25 to 29 years old (24%) (Mean age ± SD: 32.4 ± 15.6 years). The most common methods were 46% firearms, and 29% stab wounds, respectively. Among occupational deaths happened in 99% of males and 1% of females. The most common victims' age-group was 30-39 years old (25%) (Mean age ± SD: 35.8 ± 10.3 years). Seventy-four percent of cases were caused by blunt trauma as a result of falling from a height. The second common cause of death was Electrocution (21% of the cases). Conclusions: The analysis of the causes of suicidal, homicidal, occupational deaths, can aid the development of preventive strategies to decrease the occurrence of these kinds of preventable deaths in Iran.