Abstract    This paper investigates the position of subject in Persian with particular reference to freezing effects first suggested in the study of syntactic islands. The research is carried out within the framework of minimalist theory and deals with a proposal by Boeckx (2003Ø 2008). In his analysis, it is argued that once subject DPs move to Spec TP to check their Case and the EPP feature of TP, they become frozen in a checking domain. The present study has analyzed Persian data in the light of this hypothesis. The results show that freezing effects as proposed by Boeckx receive support from Persian data: Subjects disallow subextraction in this language. We, then, take a look at previous studies on subextraction from DPs in Persian and show that some Persian data are problematic for those analyses. Finally, we present an analysis based on freezing effects that supports Anooshe's (1389) analysis according to which the canonical subject position in Persian is Spec, TP rather than Spec, vP.