Background Infections have been indicated to be the cause and / or consequence of the calving and decompensation of some Connective Tissue Diseases and, in principle, both the immunological disorder and the immunosuppressive action of medications contribute to this. Objectives To describe the frequency of infections associated with the various rheumatological pathologies in patients admitted to hospitalization and to know their associated factors. Methods A descriptive study was carried out in which 3328 medical records belonging to the patients of the Rheumatology service were reviewed during a follow-up period from January 2010 to December 2020, measures of central tendency such as mean, mode, median and applied the Chi square test to appreciate statistical value between the various variables to be correlated. Results Most of the patients were female. The main rheumatological pathology was Rheumatoid Arthritis, followed by Systemic Lupus Erythematosus, Osteoarthritis in 3 place and finally in the last box other entities other than those indicated. The main infectious were those of the urinary tract, in the second instance those of skin and soft tissues, in third place the respiratory ones and lastly those not included in the previous categories. The 2 main therapies related to infections were the use of steroids followed by biological therapy (p 0.001). Table 1. Medications received, categories of infections and reason for hospitalization presented by patients in frequencies and percentages. Conclusion In the present study it was found that infections were the main cause of decompensation and hospitalization in these patients. Infection is the cause of significant morbidity and mortality in rheumatology patients. Conclusions: Based on the observations obtained in the present study, it is recommended that the risks for the development of infections in rheumatology patients be evaluated through stratification systems and thus generate strategies that reduce their frequency. References [1]D Aletaha T, Neogi AJ, Silman J, Funovits DT, Felson CO. Bingham 3rd Rheumatoid arthritis classification criteria: An American College of Rheumatology/European League Against Rheumatism Collaborative Initiative. Arthritis Rheum. 62 (2010).p.2569-2581 http://dx.doi.org/10.1002/art.27584. Medline [2]Listing J, Gerhold K, Zink A. The risk of infections associated with rheumatoid arthritis, with its comorbidity and treatment. Rheumatology, 52 (2013).p.53-61 http:// dx.doi.org/10.1093/rheumatology/kes305. Medline. [3]Galloway JB, Hyrich KL, Mercer LK, Dixon WG, Fu B, Ustianowski AP. BSRBR Control Centre Consortium; British Society for Rheumatology Biologics Register Anti-TNF therapy is associated with an increased risk of serious infections in patients with rheumatoid arthritis especially in the first 6 months of treatment: Updated results from the British Society for Rheumatology Biologics Register with special emphasis on risks in the elderly Rheumatology, 50 (2011).p.124-131 http://dx.doi . org/10.1093/rheumatology/keq242. Medline [4]Winthrop KL. Infections and biologic therapy in rheumatoid arthritis: Our changing understanding of risk and prevention. Rheum Dis Clin North Am. 38 (2012).p.727- 745 http://dx.doi.org/10.1016/j.rdc.2012.08.019 . Medline [5]Pala O, Diaz A, Blomberg BB, Frasca D. B Lymphocytes in Rheumatoid Arthritis and the Effects of Anti-TNF-α Agents on B Lymphocytes: A Review of the Literature. Clin Ther. 2018 May 22. pii: S0149-2918(18)30158-9. doi: 10.1016/j.clinthera.2018.04.016. Disclosure of Interests None declared