History and Objectives: Considering the incidence of arthritis and controversial reports regarding type, involved joint, gender and paraclinical findings and the absence of enough information for its prevalence in Iran, this research study was performed to determine the epidemiology of arthritis in children admitted to Shaheed Beheshti hospital in Kashan from 1991 to 1999.

Materials and Methods: The research was conducted on existing data on hospitalized children with an initial diagnosis of arthritis. For this purpose, their records were collected and the cases with a definite diagnosis were carefully studied. The data regarding age, gender, involved joint, type of disease and ESR and so on were recorded in questionnaire.

Results: The study was performed on 4960 admitted children and 248 (5%) out of them had arthritis. In addition, 57.3% out of them were male and 42.7% were female. Meanwhile, 3.6% had an age less than 1 year, 42.3% with an age between 1 and 5 years and 54.1% had an age greater than 5 years. The most common form was septic arthritis (23%) and this type of arthritis was observed in children under 1 year of age and its incidence was 50% in children under 3 years of age. Other kinds of disorder were reactive, brucellosis and toxic arthritis. Furthermore, all cases with an ESR greater than 100 had septic arthritis and some of the children with septic one showed a low ESR.

Conclusion: The septic arthritis is the most important and common form of arthritis, especially in children under 1 year of age. Therefore, it is recommended to perform similar studies in other region in Iran to have a thorough epidemiological evaluation.