fa عمومى General پژوهشي Research <p style="text-align: justify;"><strong>Background:</strong> Chronic mental illnesses affect cognitive status and behavior, which lead to&nbsp;social and communication impairment and behavioral problems. This research investigated the&nbsp;influence of communication skills training on aggression and quality of life of the patients with&nbsp;chronic mental illnesses.<br> <strong>Methods: </strong>This study is a quasi-experimental study with pretest and posttest. First, a total of&nbsp;30 patients with chronic mental illnesses were selected based on the inclusion criteria. Next,&nbsp;they were randomly assigned into the control and experimental groups. The experimental group&nbsp;received techniques of communication skills for 10 sessions (each session 60 minutes, one&nbsp;session per week). The research instruments were The World Health Organization Quality of Life&nbsp;and Buss&ndash;Perry Aggression Questionnaire. Statistical analysis was conducted through analysis&nbsp;of covariance (ANCOVA).<br> <strong>Results: </strong>Our findings indicated that the means of quality of life scores (F=41.62, P=0.001) and&nbsp;aggression (F=11.30, P=0.002) were significantly different between research groups after the&nbsp;intervention.<br> <strong>Conclusion:</strong> Communication skills training improve behavioral problems and quality of life&nbsp;in patients with chronic mental illnesses. Thus, it is necessary to use these skills to prevent and&nbsp;decrease behavioral problems and promote social skills in patients with mental disorders.</p> Communication skills, Chronically mental disorder, Aggression, Quality of life 3 10 http://jccnc.iums.ac.ir/browse.php?a_code=A-10-167-3&slc_lang=fa&sid=1 Anahita Khodabakhshi Koolaee a.khodabakhshid@khatam.ac.ir 10031947532846003276 10031947532846003276 Yes Department of General Psychology, Faculty of Humanities, Khatam University, Tehran, Iran Hossein Ebrahim Baighi 10031947532846003277 10031947532846003277 No Department of Clinical Psychology, Psychiatric Nursing in Chronic Mental Illness Section, Shahid Lavasani Hospital, Tehran, Iran. Ali Navidian 10031947532846003278 10031947532846003278 No Department of Community-Based Nursing Research Center, Faculty of Nursing & Midwifery, Zahedan University of Medical Sciences, Zahedan, Iran.