Languages have different strategies in formation of relative clauses (Keenan & Comrie,1977). This study investigates the relativization of different grammatical roles in Eastern dialect of Gilaki, a Northwestern Iranian language. Gilaki uses postnominal and prenominal strategies for headed relatives. The postnominal strategy relativizes all head NP positions, however, the prenominal strategy can only relativize subject and object positions. The focus of this study is on the Gilaki prenominal reduced relatives which contain participles in contrast to the postnominal relatives that are full finite clauses. According to Shagal (2019), participles are defined as non-finite verb forms that can be employed for adnominal modification. According to Krause (2001), all participles, regardless of being postnominal or prenominal are dominated by a nominal projection. Regarding Gilaki participial relatives, this study is inspired by Krause (2001) and proposes a syntactic derivation which involves the embedding of a verbal projection into a nominal category. The nominal head dominating the participle gives a nominal status to the participial modifier and makes the structural genitive case available for the subject within NP. In this way, Gilaki allows non-subject relativization without Case Filter violation or agreement mismatch.