Study aim: Determining the effect of Mindfulness-Based Stress Reduction (MBSR) program on the levels of anxiety, stress, and depression in psychiatric patients Design: Simple randomization will be used to allocate participants into two groups: an intervention group and a control group, with 48 participants in each group. Settings and conduct: In this study, eligible patients will first be identified among inpatients at Razi Psychiatric Teaching Hospital. The inclusion and exclusion criteria will be carefully assessed to ensure the selection of a homogeneous and appropriate sample for the study. After eligible patients have been identified, written informed consent will be obtained from the participants. The objectives, procedures, benefits, and requirements of the study will be fully explained to them to ensure that they participate with complete awareness. The study will be conducted using a single-blind design. Participants/Inclusion and exclusion criteria: Inclusion criteria: - Age over 18 years - Diagnosis of a psychiatric disorder by a psychiatrist - Ability to attend weekly sessions Exclusion criteria: - Patients experiencing an exacerbation of acute psychiatric disorders or suffering from an acute physical illness - Any stressful life event Intervention groups: The intervention group will receive the MBSR intervention in addition to usual care and treatments. The intervention will be delivered in semi-structured group sessions, consisting of eight 2-hour sessions. The control group will receive only usual care and treatments throughout the study period, and no MBSR intervention will be provided. Outcome assessments will be conducted at the same time points as in the intervention group. Main outcome variables: **Mindfulness-Based Stress Reduction (MBSR)**