Question: What is your ruling on an autopsy of a deceased Muslim?
Answer: It is not permissible to perform autopsy on the body of a dead Muslim for the sake of education and other purposes. It is only permissible, if the life of another Muslim depends on it—even if it is sometime in the future.
Question: In certain cases, some governmental agencies demand that autopsy be performed on the body of the deceased to establish the cause of death. When is it permissible to agree to their demand and when is it not?
Answer: No heir of a deceased Muslim is allowed to give consent for autopsy to be carried out on the body of the deceased for the purpose mentioned above and other similar purposes; and it is necessary for him to prevent the autopsy if possible. Of course, if another important factor at play that of equal or more importance than this basic rule such as securing the life of an innocent individual Muslim, it is permissible.
Ayatollah Al-Sayyid Ali Al-Husseini Al-Sistani