IntroductionSacroiliitis is one of the important symptoms in patients attending infectious diseases and rheumatology clinics. Some patients with sacroiliitis are asymptomatic, and some have unspecific symptoms. The aim of this study was to determine the frequency of sacroiliitis causes among patients attending Shahid Sadoughi’s infectious disease and rheumatology clinics.MethodsIn this study, we evaluated patients attending Shahid Sadoughi rheumatology and infectious diseases clinic in 2014. Patients who had positive findings in favor of sacroiliitis were evaluated by history, physical exam, laboratory tests, and imaging. The patients were divided into infectious, inflammatory non-infectious, and degenerative causes. The data were analyzed by IBM SPSS version 20 using the independent samples t-test, ANOVA, the chi-squared test, and the Fisher’s exact test.ResultsWe studied 136 patients. Among them 64 (47.1%) were male, and 72 (52.9%) were female. The mean age of the participants was 34.28 ± 10.36 years. Among the patients, 12 (8.8%) had infectious causes, 120 (88.2%) had inflammatory non-infectious causes, and four (2.9%) had degenerative causes.ConclusionBased on our results, inflammatory non-infectious causes are at the top of the list of sacroiliitis causes, but we should always consider infectious causes, including brucellosis.