The present study was conducted to investigate the effect of verbal intelligence on Iranian pre-intermediate students’ knowledge of lexicon. The participants comprised of 30 male and 30 female learners. A vocabulary test was administered to find out students’ vocabulary knowledge and also Wechsler intelligence test was administered for both groups of male and female to find out students’ verbal intelligence, of course the verbal part of intelligence was needed due to the topic of study. Analysis of the result revealed that the participants who had higher verbal intelligence also had higher marks in vocabulary test and the participants who had lower verbal intelligence had a lower mark in vocabulary test.