Abstract Vocabulary is the basic access to language; however, language beginners may not be good at applying methods to help them memorize words. The main objective of this study was to compare the effect of semantic mapping strategy on forty Iranian EGP learners’ vocabulary mastery. The participants were randomly assigned to a control group that received traditional direct translation and the treatment group that received instruction on semantic mapping. In order to assess the efficiency of the strategy, a pre-test and post-test was administrated to both groups. The results show that using semantic mapping strategy resulted in a significant difference in the participants’ vocabulary learning.