The aim of this study is to examine the use of Mneumonic techniques in teaching vocabulary mastery. This research was accomplished among seventh grade students of Mts Al-Huda Mubung in the 2021/2022 akademic year. This study is a pre-experimental research design with pre-tests, treatments, and post-tests. Data is collected applying a multiple choice test. The research sample was taken from seventh grade students, which contain of 24 students. Research results show that the average score of students pre-test is 48.5 while post-test is 67.66. It appeared that the student's performance has improved after the treatment. In this study, the writer uses the t-table a (0.05) with degrees of freedom of 23 or 2069 while the result of the t-test is 27.46. This means that the t-test is higher than the t-table (10.33 > 2069). The resulting effect size (ES) is 1.85, which is classified as a strong effect. It appeared that the null hypothesis has been rejected and the alternative hypothesis is accepted. This also proves that the use of Mneumonic Technique effect eminently the students' vocabulary mastery.
