The existing division [of things] into ‘ immaterial’ and ‘ material’ is one of the important and vital divisions in philosophy. Paying attention to it will answer many philosophical problems. Muslim thinkers have discussed material and immaterial beings in their works and have presented definitions for them. In their definitions, they have stated features of the immaterial and material beings and the criteria for distinguishing them. Scrutinizing those criteria and their foundations would reveal challenges. In the present article, by reviewing and investigating criteria such as matter, quantity, form, state, length, width, volume, color, being in the matter and being with the matter, potentiality, change, motion, capability of being externally divided, time, place, personality and particularity, put forward by Muslim thinkers, a new criterion for distinguishing material beings from immaterial ones is established based on which a material being is a being that is perceived through senses or is dependent on it. An immaterial being, however, is a being neither sensible through senses nor dependent on it.