Depression remains one of the world's most urgent health problems, affecting an estimated 350 million people. Mindfulness is effective for people suffering from critical depressive symptoms. The aim of this study was to evaluate the effectiveness of mindfulness training techniques on stress, anxiety, and depression of depressed patients. Design: -Quasi-experimental design (one group pretest-posttest design) was used to achieve the aim of the study. Setting: -The study was conducted at the Psychiatric Hospital in Tanta and The Psychiatric and Addiction Treatment Hospital in Met-Khalf, Menoufia governorate, Egypt. Sample: -A Purposive sample (34) depressed patients that were diagnosed by psychiatrists according to DSM5 were selected; in the chosen setting inpatient clinics. Tools: Data were collected using the depression, anxiety and stress scale. Results: The results revealed that there is a highly statistically significant reduction in stress, anxiety, and depression mean score level among the study group after mindfulness training techniques than before; where p-value (p = 0.001). Also, there is a statistically significant positive correlation between stress and depression level of study group before and after mindfulness training techniques where p-value (p = 0.015, 0.013), respectively. Conclusion: The implementation of mindfulness training techniques with depressed patients has a positive effect on reducing stress, anxiety, and depression levels. Recommendation: Application of mindfulness training techniques for all patients with depression to reduce their stress, anxiety, and depression levels.