Down syndrome is associated with the risk of various structural abnormalities or functional disturbances of organ systems, and with several abnormalities of the immune system. Screening and monitoring of congenital heart defects or orthopedic problems are managed and the increased risk to develop leukemia, diabetes of hypothyroidism is well known. The 3 to 6-fold incidence of juvenile idiopathic arthritis in Down syndrome compared with the general juvenile population is, however, less known. We describe a patient, for whom the diagnostic delay of juvenile idiopathic arthritis was eight years.