One of the most famous and most important doctrines of Ibn Sina’s metaphysics is the distinction between essence and existence: a pivotal and controversial one. On the one hand, this distinction paves the way for some new metaphysical innovations to be introduced, but on the other hand it gives way to serious criticism to be levelled against Ibn Sina’s philosophy. Meanwhile, an issue that has not been yet been resolved is whether this is a conceptual or ontological distinction and if it is ontological whether it has a nonessential signification or not. After reviewing the different views on this problem and representing a clear depiction of the point of controversy, this study shows that although all metaphysical solutions of Ibn Sina are not based on this distinction, there are some textual evidence and some solutions which imply this distinction. Then, by analyzing the concept of “addition’’ as a central concept to explain the realization of essence and existence in the external world, it is demonstrated that in Ibn Sina’s metaphysics, this concept does not imply the dependence of existence to essence. In fact, addition means that both essence and existence are realized in the external world in a manner that existence entails essence.