Diaphragmatic breathing technique has been known for its beneficial effects on physical and psychological health. This technique has been used widely as an intervention for people with some psychological problems such as Alzheimer and ADHD. There is still very limited research conducted on the use of the technique on normal population. Hence, this paper reports a research that aim to examine the effect of diaphragmatic breathing technique on stress and memory performance of Tahfiz students or students who memorizes Quran. It was hypothesized that practicing diaphragmatic breathing technique would reduce the stress level and increase the memory performance of the students who memorize the Quran. The research methodology involves the use of a within-group experimental design on 50 IIUM undergraduate Tahfiz students. Students’ stress level is measured using Perceived Stress Scale while the memory performance is measured using Words Recall Test. Based on the analysis using paired-sample t-test, it has been found that practicing diaphragmatic breathing technique give positive impact on students’ stress level and memory performance. The findings from this research provides some evidences on the effects of using diaphragmatic breathing techniques for improving the psychological well-being of students who memorize the Quran.