Abstract. The current study examined the way adult Iranian EFL learners resolve relative clause attachment ambiguities, for example, in sentence: Someone saw the maid of the actress who was on the balcony. The main problem posed by those sentences is that the learners fail to process the ambiguous sentences, in fact, they don’t know that which noun they should prefer the attachment? 100 Inter-mediate Persian learners of English ( Aged 15 up to 21) recruited from two English language Centers in Qazvin, a province in Iran. Safiran and Apple Institute, the participants are asked to take part in an off-line questionnaire study, they replied to English off-line questionnaire. Their performance was revealed by the answers. the results indicated that Iranian EFL students do not opt for low attachment in resolving relative clauses, rather they choose high attachment in resolving relative clauses. An implication of these findings is that there is semantic relationship between the two options or possibilities which the parser tries to analyze them.