The research was based on this question: What is the effect of summarization strategy training on Iranian EFL learners' reading comprehension? And the fallowing hypothesis raised: Summarization strategy training has no effect on reading comprehension. According to obtained results, null hypothesis is rejected. That is to say, summarization strategy as a cognitive strategy affects reading comprehension of the ESP learners. Comprehension of text is a vital aspect in reading; it allows the reader to fully understand what is being read. Teaching summarization is another way to improve overall comprehension of text.