Introduction: Abortion is one of the basic and definite decrees, to which the book and the tradition imply, but, as any basic decree in case of secondary circumstance, it can be changed in the same way and the abortion is possible. The aim of this study was to evaluate the jurisprudential foundations of abortion permission with an emphasis on jurisprudential rule of incompatibility.
Conclusion: Some Imamieh jurists believe that only when the soul has not been blown up in fetus and that the mother's life is preceded by abortion, according to the rule of incompatibility, abortion is permissible. Another group believes that the fetus can be aborted even after blowing the soul in fetus to defend the mother's life. Some others, based on the rule of incompatibility, consider a mother entitled to abortion and pay more attention to mother's life, but if the life of mother and fetus are of equal importance, according to the rule of incompatibility and doubt about the requirement, if there is no superiority on one of the two sides, the wisdom is to decides and the pregnant woman is between the survival of her own self and abortion. From Imamieh jurists’ point of view, if the survival of fetus involves maim or an intolerable pain for mother, for the health of mother, abortion is permissible before the soul is blown up. Others believe that mother can be treated even with blowing the soul in fetus and does not need to delay it; even if the treatment causes an abortion and they say, according to the rule of incompatibility, that the mother’s life has a preference.