Background & Aim: the most common causes of sudden death are cardiac causes, this setting, myocarditis is considered as a cause of sudden death, especially in young age groups. This is obvious that diagnosis of myocarditis in sudden death is possible only by an autopsy and histopathology examination. With Myocarditis diagnosis and determining groups in danger, consequently, we can task steps in Ideal remedy for precaution and proper diagnosis. Materials & Methods: In a descriptive retrospective study (case series type) of 62 corpses with sudden death referred to legal medicine organization of Iran (Tehran's center), between 1379-1381, wich in them myocarditis had been confirmed by histopathological evidences in autopsy, we studied some of underlying factors including; age, gender, the history of addiction, underlying diseases, the season of sudden death occurrence, cardiac and non-cardiac accompanying pathologies, and the agreement between clinical and histopathological diagnosis.Results: The mean age was 27.5±18.1 years and the greatest and least frequencies of sudden death were in 21-40 years old and>60 years old 65.5% of them were male, respectively. We did not found a significant seasonal variation of sudden death among seasons. From the point of underlying disease, a great percentage of the studied sample had a history of infection (mostly respiratory infection) just before the sudden death (37.1%), following by perioperative complications (9.7%), and a history of trauma (6.5%). The history of opioid addiction (35.5%). in autopsy, cardiac appearance in the majority of cases was normal (63.9%). The most common accompanying cardiac pathologies were: pericarditis (11.3%), and the most accompanying non-cardiac pathologies were: pneumonia and/or bronchopneumonia (53.2%). By clinical decision, the causes of sudden death had been diagnosed only in 19.4% cases.Conclusion: young age, history of infection and drug addiction are risk factors for myocarditis. It isn't properly diagnosable in bedside.