A great number of people in west of Iran, east and northeastern Turkey, Iraq, Syria and Caucasian speak in Kurdish language. Kurdish is a branch of Indo – European language, a sub group of the Iranian language Kurdish is generally divided into three groups: the biggest group is the northern Kurdish, called Kurmānjī, spoken by the Kurds living in Iran, Turkey, Syria. The central group, called Soranī, includes those people who live in the northeast of Iraq. The south group includes the Kurdish language spoken in Iran, Kirmanšā, Dālāhū, Iraq, and Halabča. This study aims at surveying the phonological system of Kurdish language. The finding of the study shows that the phonological system of Kurdish language has preserved some Old Iranian phonemes in its spoken form. For example, x_ which existed in Old Persian words such as x_ar (sun) still exists as a phoneme in Kurdish lexical item such as x_aš (happy) but not in modern Persian. Other findings show the existence of some other Old Iranian vowels and consonants in Kurdish.
