This study was an attempt to find out the impact of Montessori teaching method on EFL learners' writing achievement. To fulfill the purpose of the study, out of 150 students, 95 male and female students were selected randomly to participate in this study. All of them were given a pretest to find out their level of proficiency. They had no background knowledge of English and they had not studied English before. They were also divided randomly into two groups namely experimental and control. The experimental group consisted of 23 male and 27 female learners while the control group consisted of 21 male and 24 female learners. Experimental group members were instructed based on Montessori teaching method and their instruction was based on different Montessori materials. The control group members had a routine teaching process. Each group was a mixture of both male and female learners with the age range of 5-6. After 12 sessions, writing posttest was given to both groups to evaluate whether there is any significant difference between these two groups or not. The obtained data were analyzed both descriptively and inferentially. The data were analyzed by statistical tests such as one-way ANCOVA and one-sample t-test. The statistical analyses revealed that there was significant statistical differences between two groups mean scores on the writing posttest. Therefore, it can be argued that Montessori teaching method had significant impact on learners' writing skill.