Vowel sounds along with consonants constitute the sound system of each language throughout the World including English. Among various accents in English language, Received Pronunciation (RP) accent is widely used as a model for the teaching system in Kurdistan Region of Iraq by which Kurdish EFL learners use this standard accent in their academic life. Accordingly, there are various kinds of mistakes that are done by Kurdish students when they attempt to pronounce vowels (monophthongs). To investigate their performance and improvement of pronouncing vowels, 20 Kurdish EFL learners studying their undergraduate degree in English language at the University of Duhok were examined using a word list as well as a passage containing vowels. We found that the central vowels are the most affected or mispronounced vowels among the monophthongs followed by back vowels and front vowels respectively. The obtained results highlights the significant differences between Kurdish and English vowels and subsequently may provide a basis for identification of common mispronunciations that are usually done by Kurdish EFL learners which has a great academic value.