Self-stigma remains one of the most vexing issues in psychiatry. It complicates the treatment and social functioning of patients with endogenous psychiatric disorders. Identifying the specific features of self-stigma depending on the type and duration of the endogenous mental illness can help solve this problem. The aim of this study was to establish the level and specific features of self-stigma in patients with various types of chronic endogenous psychiatric disorders at different disease stages and to establish the correlation between the level of self-stigma and the attitude of the patient to his/her disease and treatment. Clinical psychopathology assessment, psychometric scales and questionnaires: "Positive and Negative Syndrome Scale" (PANSS), "Questionnaire for Self-Stigma Assessment in Mentally Ill Patients", and Russian versions of the "Insight Scale for Psychosis" (ISP), and "Drug Attitude Inventory" (DAI-10). The cross-sectional study included 86 patients with endogenous mental illnesses (bipolar affective disorder and schizophrenia spectrum disorders. The analysis of the results of the "Questionnaire for Self-Stigma Assessment in Mentally Ill Patients" showed that at the initial disease stages the highest level of self-stigma is observed in patients with bipolar affective disorder (M±σ=1.22±0.73; Me [Q1; Q3]=1.10 [0.83; 1.60]), while the lowest level was observed in patients with schizophrenia spectrum disorders (M±σ=0.86±0.53; Me [Q1; Q3]=0.77 [0.31; 1.25]). Patients with schizophrenia and schizoaffective disorder and a disease duration more than five years participating in a long-term comprehensive psychosocial rehabilitation program also demonstrated high rates of self-stigma (M±σ=1.20±0.57, Me [Q1; Q3]=1.26 [0.89; 1.47]). The study groups showed differences in terms of the structure of components of self-stigma and their severity; significant correlations were uncovered between the self-stigma parameters and the attitude of patients to their disease and therapy. The results of this study contribute to a better understanding of the specific features of self-stigma in patients with various endogenous disorders at different stages of the disease. These data can be used as part of a comprehensive psychosocial treatment program for this patient cohort, as well as for future research.