The non-overt subject of the infinitive clause is represented by the element PRO, an NP which appears to be syntactically active without overt manifestation. Although PRO is a part of architecture of GB, no coherent account of this element can be found in Persian. The stipulation of PRO by Iranian grammarians both traditional and modern has been in vain due to two dilemmas: first the nature of non-finite clause in Persian, and second, finding ungoverned position for PRO. After all, syntactic, semantic and morphological behavior of Masdsar in Persian supports its constituency nature in favor of being a non-finite clause. Subsequent to introducing the non-finite clause in Persian, there will be a room to account for the existence of PRO. Of considerable importance is the justification that non-finite clauses are CPs not IPs, which makes it possible to find an ungoverned position for the distribution of PRO.