This study examines the effect of computer-assisted language learning on the vocabulary learning of Iranian EFL learners, in which 40 pre-intermediate and intermediate students enrolled at Iran Language Institute, Urmia, Iran were selected as participants. The participants were randomly assigned to two experimental groups and two control ones. The two experimental groups underwent the same procedures in receiving treatment, while the control groups did not receive any treatment. Initially, all groups participated in pre-tests. The students in the experimental groups were exposed to the treatments for eight sessions, which included the teaching of word lists selected from the students' books using computers. These words were taught to the experimental groups using 'Vocaboly', while the control groups were taught using the traditional method of vocabulary teaching. Finally, all groups participated in post-tests. The comparison of the mean scores using a t-test indicated that the experimental groups outperformed the control groups on post-tests.