Vowel harmony (VH) is a phonological rule which is mainly related with the vowels, though some degrees of harmony exist between vowels and consonants and also between some consonants in the dialects of Azerbaijan Turkish in Iran . The purpose of this paper is to study the treatment of vowel harmony in the dialects of Azerbaijan Turkish in Iran. In fact, the researcher has made an attempt to find a reliable answer to the question "Is vowel harmony realized in the speech of the Azerbaijan Turks in Iran?" Using the necessary linguistic data collected from the inforants of the dialects and within the framework of generative phonology, the author of the paper has attempted to evaluate the present-day situation of vowel harmony in the above-mentioned dialects of Azerbaijan Turkish (a synchronic study). The results of the study showed that, except some violations mostly observed in the loanwords, there is an innate harmony in the roots of the words and a stronger and more stable harmony between the roots and the suffixes of these dialects, so vowel harmony is realized in these dialects to a relatively high degree. The study demonstrates that vowel harmony is a major and distinctive phonological rule in these dialects.