The third person reflexive pronoun in Italian, phonetically realized as "si", has a usage called impersonal subject in the traditional grammar, where it refers to generic people or persons specified in the speech situation. This pronoun has several characteristics which are not observed in other usages of the reflexive pronoun, which suggests that it should be considered as an independent morpheme. In this article we present the syntactic properties of this element, which we call impersonal reflexive pronoun (SI), in the framework of Minimalist Program. We propose the following: SI has the nominative Case feature; it assumes a θ-role as an argument; and it is merged in an A-position. Its morphological property forces it to move to the head position in TP, where its Case feature is properly checked. The Spec TP position in this construction is empty and the EPP feature of T is checked against SI situated in T itself. As for its peculiarity in the agreement phenomena, we suppose that its gender and number feature is [+masculin, +plural], whereas its person feature is [third person singular]. With these assumptions, the complex distribution of SI is explained in a straightforward way and its syntactic status is explicitly established.