The study aims to investigate the effectiveness of a brain-based learning program in improving intermediate level B+ Al Azhar English Training Center students' argumentative writing. The study began with a review of literature and related studies dealing with EFL argumentative writing and the brain-based strategies which can teach arguments. The researcher prepared a list of the argumentative sub-skills regarding the students' needs and the CEFR rubrics and framework. Jury members of ILETS instructors and TEFL professors ascertained the appropriateness of the targeted sub-skills. The study adopted the experimental approach, three instruments were constructed and tested to fulfill the purpose of the study. the argumentative sub-skills were tested twice using the pretest and the posttest to measure the students' performance before and after applying the program. The study sample consisted of 56 B+ intermediate-level students of Al Azhar English Training Center, Al Azhar University, Cairo Governorate Which is academically run by the British Council according to a partner-ship with Al Azhar. The results revealed that, in terms of the development of the argumentative writing test, there is a statistically significant difference between the mean scores of the study participants on the pre and post-tests, as a total score in favor of the post-test scores. The findings showed the effectiveness of the brain-based learning program in developing the argumentative writing of Al Azhar AAETC intermediate-level students. The study recommended using brain-based learning in developing other writing genres in the IIELTS writing test and speaking sub-skills.