This study investigates the effect of noun and verb categories on second language (L2) pronunciation of Iranian adult EFL learners. The participants were native speakers of Farsi and were at the intermediate level. They pronounced 20 sentences matched for the phonetic content and frequency and contained areas of pronunciation difficulty for EFL learners. Each participant's pronunciation was audiotaped and submitted to two raters so as to pinpoint mispronounced phonetic segments in the data. Results revealed that the participants had difficulty in pronouncing the phonemes non-existent in their L1. The most common errors were epenthesis, substitution errors, and vowel shortening/lengthening, and more pronunciation errors were produced in verbs than nouns. The findings may present to the EFL teachers a set of general ideas about the possible problems that L2 learners may encounter in pronunciation.
