This study aimed at investigating the effect of using the technique of mind maps on enhancing preparatory school students' EFL vocabulary. The quasi experimental design was adopted as there were 60 participants in preparatory grade two. They were randomly divided into two groups; the treatment group (N= 30) and non-treatment group (N=30). The treatment was conducted during the first term of the scholastic year 2021/2022 in one of the preparatory schools at Beni-suef Governorate. The treatment group participants were taught using the technique of mind maps whereas the non-treatment group students received the same course through the usual techniques. The results revealed that there was a statistically significant difference between the mean scores of the treatment group and non-treatment group in the post administration of the vocabulary test in favor of the treatment group. In addition, it was concluded that using the technique of mind maps is effective in enhancing the preparatory school students' vocabulary.