en Clinical Neuroscience Clinical Neuroscience Original Original <strong>Introduction</strong>: Generalized Anxiety Disorder (GAD) is one of the most common anxiety disorders that has significant adverse effects on social functioning, occupational/academic performance, and daily living. This study aimed to evaluate the effect of Quantitative Electroencephalography (QEEG)-based Neurofeedback (NFB) therapy on anxiety, depression, and emotion regulation of people with GAD.<br> <strong>Methods</strong>: This research is a quasi-experimental study with a pre-test/post-test/follow-up design and a control group. The study participants were 29 college students with GAD living in Zanjan City, Iran, who were selected using a convenience sampling method. Then, they were randomly divided into two groups of intervention (n=15) and control (n=14). The protocol of NFB therapy was designed based on the QEEG method. The intervention group received QEEG-based NFB therapy for 8 weeks (20 sessions, 2 sessions per week, each session for 45 min), while the control group received no intervention. The samples were surveyed and measured by using a 7-item GAD scale, Emotion Regulation Questionnaire (ERQ), 21-item Depression, Anxiety, and Stress Scale (DASS), and Structured Clinical Interview for DSM (SCID) before and after the intervention and then at a 3-month follow-up. The collected data were analyzed in SPSS software V. 22 using univariate ANCOVA and repeated measures ANOVA.<br> <strong>Results</strong>: The within-subjects effect of time (pre-test, post-test, and follow-up) was statistically significant (P=0.031). The intervention group showed significant changes in the post-test and follow-up phases in comparison with the control group. The anxiety and depression levels of patients reduced significantly (P=0.001), and their emotion regulation improved (P=0.001) after the intervention, and they remained unchanged in the follow-up period.<br> <strong>Conclusion</strong>: QEEG-based NFB therapy can reduce anxiety and depression and improve emotion regulation in patients with GAD. Quantitative electroencephalography, Neurofeedback, Generalized anxiety disorder, depression, Emotion regulation 281 290 http://bcn.iums.ac.ir/browse.php?a_code=A-10-2378-1&slc_lang=en&sid=1 Hassan Abdian lavinramezani@yahoo.com 13700319475328460033984 13700319475328460033984 Yes Department of Clinical Psychology, Faculty of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran. Mazaher Rezaei 13700319475328460033985 13700319475328460033985 No Department of Clinical Psychology, Faculty of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran. Zakaria Eskandari lavinramezani@yahoo.com 13700319475328460033986 13700319475328460033986 No Department of Clinical Psychology and Addiction Studies, Faculty of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran. Shokoufeh Ramezani lavinramezani@yahoo.com 13700319475328460033987 13700319475328460033987 No Department of Educational Sciences, Faculty of Humanity, University of Mohaghegh Ardabili, Ardabil, Iran. Reza Pirzeh 13700319475328460033988 13700319475328460033988 No Department of Pschiatry, Faculty of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran. Mohsen Dadashi lavinramezani@yahoo.com 13700319475328460033989 13700319475328460033989 No Department of Clinical Psychology, Social Determinants of Health Research Center, Zanjan University of Medical Sciences, Zanjan, Iran.