OBJECTIVES: The objectives were to examine the association of the serological profile of autoimmune antibodies with the clinical features and outcomes of the disease in patients with IIM, the importance of MSA in establishing the diagnosis, then to examine the occurrence of malignant diseases in patients with IIM and the effect of therapy on the course and outcome of the disease. STUDY DESIGN: Cross-sectional study with historical data. MATERIAL AND METHODS: The research subjects are patients of both sexes and all age groups, suffering from IIM, who were treated in the period from January 1, 2017 to December 31, 2021 at the Department of Rheumatology, Clinical Immunology and Allergology at KBCO. Data were collected by reviewing patient data in the BIS. The age and gender of the patients, data on diagnostic parameters (CK, myoglobin, MSA, MAA), data on affected organs and organ systems, and malignancies associated with myositis were recorded. RESULTS: Out of a total of 28 patients with IIM, 71,43 % were female and 28,57 % were male. Arithmetic mean age of all patients is 60,9 (SD = 13,9), ranging from 24 to 78 years. In addition to myositis, the majority of patients had associated diseases or affected organ systems (hypertension, involvement of the skin and bone-joint system). Patients with a positive Anti-Jo-1 antibody had 0 – 4 organs affected, while those with positive other antibodies (ENA screen) had 4 – 9 organs affected. In 39,3 % of patients, 21,4 % were diagnosed with malignant and 17,9 % with benign disease. 17 patients are currently in remission, 10 patients achieved remission with a medium high dose of glucocorticoids. CONCLUSION: There is an association between the serological profile of autoimmune antibodies with clinical features and disease outcomes in patients with IIM. Patients diagnosed with IIM may have an increased risk for malignancies. All patients were treated with glucocorticoid therapy, and no statistically significant difference in the dose of glucocorticoid was found on the course and outcome of the disease in patients with IIM.