RESUMEN
Background: In Iran, there is a lack of information and studies on acute rheumatic fever (ARF), a global health issue. The limited understanding of ARF's prevalence and primary clinical symptoms has led to confusion. This research investigates the characteristics of children aged 3-17 years who experience ARF with monoarthritis as their initial symptom. Methods: A retrospective evaluation of medical records of children diagnosed with ARF was conducted. The study aimed to determine the prevalence of monoarthritis as the first manifestation of ARF and its association with age, gender, family history, and cardiac involvement. Categorical variables were analyzed using the chi-square test with a significance level of < 0.05 and a confidence interval of 95%, using SPSS software (Version 23). Results: The study included 62 patients with ARF, comprising 41 (66.1%) boys with an average age of 8.48±3.27 years. Among these patients, 12 exhibited cardiac involvement according to the revised Jones criteria, with 5 clinical carditis and 7 cases of subclinical carditis. Monoarthritis was the initial symptom in seven patients (11.29%); five (71.4%) also had carditis. There was a significant association (p<0.001) between monoarthritis and carditis. Conclusion: The study concludes that monoarthritis may be an early sign of ARF in children and correlates significantly with cardiac involvement. However, more extensive research with more significant participant numbers is necessary to understand ARF in Iran comprehensively. A thorough cardiac examination is also crucial for patients with ARF and monoarthritis.