The purpose of this paper is to study the violations of vowel harmony (disharmony) in the dialects of Azerbaijan Turkish in Iran. The researcher has made an attempt to find a reliable answer to "Are there any violations in regard with vowel harmony in the speech of the Azerbaijan Turks in Iran?" The author, based on the linguistic data, has attempted to find and show the violations of vowel harmony and the related causes in the dialects of Azerbaijan Turkish in Iran (a synchronic study). The results of the study showed that the existing violations are mostly observed in the loanwords, though we observe some violations in some of the native words, too. The writer comes to the conclusion that to minimize the degree of the violations, the use of loanwords should be avoided as far as possible, especially in the cases where there are equivalent native words.