This paper considers the conception of material cause according to Alexander of Aphrodisias. I defend the view that Alexander tries to conciliate two conceptions of material cause which are often confused in Aristotle: the concept of material cause as conditio sine qua non and the concept of material cause as a genuine cause (as 'because', dia ti). In his De fato and in his commentary on chapters 2 and 24 of book Delta of Aristotle's Metaphysics, Alexander analyses the three Aristotelian elements of material cause, namely (1) the ex hou (the 'out of which'), (2) the enuparchon (internal constituent) and (3) the hupokeimenon (substratum), and confirms the Aristotelian conception of material cause as the condition of becoming and existence of items. But explaining that material cause seems to be rather a conditio sine qua non, in his commentary on book Beta of Metaphysics Alexander explains also that, for this reason, it is less a cause than the other Aristotelian causes.