Background: During the Covid19 pandemic, patients with multiple myeloma (MM) are particularly vulnerable due to the characteristics of their disease. Aims: The aim of study was to analyze clinical and laboratory characteristics, course and outcome of Covid19 infection in patients with multiple myeloma. Methods: The study included 53 patients with MM and Covid 19 infection, diagnosed during period March 2020 - November 2021 (27 male; 26 female, mean age 62 yrs, range 37- 87 yrs). IgG MM was present in 28pts (53%), IgA in 8 (15%), IgM in 3pts (6%), and BJ in 14 (26%). According to the clinical stage (CS, Durie-Salmon), distribution was as follows: III 44pts (83%); II 4pts (8%); I CS 5pts (9%). Renal impairement existed in 18pts (34%). Regarding ISS score, the group included: ISS1 had 18pts (34%), ISS2 12pts (23%) and 23pts (43%) had ISS3. According to the Revised ISS (R-ISS) score, R-ISS1 was found in 9pts (17%), R-ISS2 in 20pts (58%) and R-ISS3 was present in 13pts (25%). All pts were treated according to National Protocol for the Treatment of Covid19 infection, including: antibiotics in 53pts (100%), corticosteroids in 50pts (94%), low molecular weight heparin in 52pts (98%), and intravenous immunoglobulins in 26pts (49%). During period January 2021 - November 2021, 9 of 24pts (37.5%) were vaccinated against Covid19. Variables of importance were analyzed using descriptive and analytical statistics. All calculations were made in SPSS program version 26.0. Results: At the moment of detected Covid19 infection, 37pts (70%) had active MM, and 16pts (30%) were in the state of follow-up during remission of disease. Immunoparesis was present in all of 37pts (74%) with active MM. Elevated interleukin-6 (IL-6) was found in 19pts (36%), of which 15pts (78.9%) had active MM. Similarly, elevated d-dimer was found in 46pts (87%), of which 35pts had active disease. During the course of Covid19 infection, pneumonia was registered in 52pts (98%), bleeding in 2pts (4%) and thrombosis in 4pts (8%). Bleeding and thrombosis were registered in patients with active MM. In the Intensive Care Units were treated 7pts (13%), with lethal outcome of 6pts. In the Semi-Intensive Care were treated 36pts (64%). A total of 36pts (64%) were cured and 17pts (36%) died. The average time to recovery of our pts was 14 days (max up to 45 days). After recovery 20pts (55%) had active myeloma, reinfection was found in 5pts (13.5%) and they were in active phase of disease. All of 5pts (10%), who were previously vaccinated against Covid19 during MM remission, completely recovered from Covid19 infection. Additionally, 4pts (8%) were vaccinated after recovery from Covid19 infection. Patients with active MM had signficantly worse outcome of Covid19 infection, (Chi-Square, p=0.003). Immunoparesis was highly frequent in pts with acitive disease (Fisher Exact Test, p=0.000), as well as elevated d-dimer (Fisher Exact Test, p=0.002). Increased IL-6 was observed in pts with active MM, but statistical significance was not established (Chi-Square p=0.088). The poor treatment outcome of pts with MM and Covid 19 was influenced by: Age (T-Test, p=0.022), Renal impairement (Chi-Square, p=0.032), and high R-ISS score 3 (Mann Whitney, p=0.042). Summary/Conclusion: A significantly worse outcome of Covid19 infection may be expected in patients with active MM and renal impairement, accompanied with findings of elevated d-dimer and IL-6, as well as immunoparesis and R-ISS score 3. All vaccinated patients recovered from Covid 19 infection.