This study attempted to find the relationship between providing Persian equivalents of English adjectives and Iranian EFL learners' active vocabulary. To this end, 100 students studying English as a foreign language at a Language Institute in Shiraz were asked to participate in this study. Participants were divided into experimental and control groups with 50 participants in each. The sample was homogenous with regard to their English level. To investigate the possible effects of providing Persian equivalents of English adjectives on Iranian EFL learners' active vocabulary, an independent Sample t-test was run on the vocabulary scores of 100 students. After analyzing the data it was found out the performances of all the participants in the “Experimental” group were better than those in the “Control” group.