Acquisition of verbs and their syntactic and semantic properties can act as the core of any sentence across languages. EFL learners encounter learnability problems in the perception of English verbs' argument structures manifested by different verbs. The current study aimed at investigating and diagnosing the problems Iranian EFL learners face when perceiving English verbs argument structures. A sample of 75 students majoring in English took part in this study. In order to answer the research questions, an Oxford Placement Test was conducted first to obtain three different proficiency levels: elementary, lower intermediate, and upper-intermediate. A Grammatical Judgment Test was administered one week after the test of proficiency to assess the learners' perception of English verbs argument structures. The data then were analyzed using descriptive statistics and also One-way ANOVA. The obtained results revealed that students with different proficiency levels perceived English verbs' argument structure differently and also they have encountered severe problems in perceiving transitive verbs, and the accomplishment type was the most problematic semantic categories in Iranian EFL learners' perception. More exposure to language input, explicit teaching of the argument structures along with their semantic and syntactic categories, and practicing in different contexts can improve the learners' knowledge of argument structures.