The present article is to describe and analyze some phonological processes of Gilaki dialect io Rudsar. The data have been collected through a five-hour interview with ten Rudsari informants. Furthermore, one of the authors of this article is a native speaker of this dialect. Besides, written sources have been used for gathering a number of data. Then, the data is transcribed according to the IPA and analyzed descriptively. The phonological processes which are studied in this article, include different types of assimilation(consonant assimilation, vowel harmony), deletion(deletion of final consonant, deletion of medial consonant), changing the cluster]-nn] into[ -nd-], lenition, metathesis, compensatory lengthening, lateralization of frl, and raising of fa! into[o] in some contexts. Sufficient evidence are presented for each process. One of the main results of this paper is that assimilation, deletion, lenition are the most frequent processes and changing the cluster [-nn] into[ -nd-jis the least frequent one in this article.