Suhrawardi's ideas on the Categories are important and form one of his innovations concerning his polemic against some of the views held by the Peripatetic philosophers. In his Peripatetic works, Shaikh al-Ishraq (Master of Illumination) reduces the ten Aristotelian Categories into five ones. He accepts substance, quantity and quality as Categories. Then, Suhrawardi classifies the five notions of time, place, posture, state and relation into the relation Category while considering the two notions of action and affection as one single Category, namely motion.
 In the first step, this essay refers to the fact that Suhrawardi's project regarding the Categories were –at least- partially reflected in the works by previous Stoic philosophers such as Avicenna, Bahmanyar, and ibn-Sahlan as-Sawi, though, introducing himself as the pioneer of this project. Shaikh al-Ishraq never mentions such backgrounds. Second, we aim to explain Shaikh al-Ishraq's remarks, unique understanding of the categorization of inherent subjects, his methodology in reaching the Categories, arguments made in defense of his project and the importance he applied to the Categories.