This research aimed to probe the impact of a Grammar Learning Strategies (GLS) module on improving the use and retention of grammar rules among the EFL majors at the Faculty of Education, Al-Azhar University. The experimental method (the pre-posttest non-equivalent group design) was employed. The participants, totaling 56, were randomly assigned into an experimental group (29) who studied the GLS module and a control one (26) who studied the usual content. The instruments of the research encompassed a grammar test assessing both the use and retention of the grammar rules and an inventory assessing the participants' use of the GLS. Results revealed the effectiveness of the GLS module in developing the EFL majors' use and retention as the effect size of the treatment was 1.01 and 0.95 respectively. Results also revealed a positive correlation between the learner's use of the GLS and grammar achievement. The research recommended integrating the GLS in the EFL curriculum so as to enhance the grammar learning outcomes as well as emphasizing the strategy use for better contextualizing the grammar rules in real-life applications.