Considering that destructive articular lesions may occur in the first stages of the illness, it is difficult but necessary to establish a diagnosis of Juvenile Idiopathic Arthritis (JIA) in due time. The authors present the case of a 9-year-old girl admitted to the Pediatrics Clinic of the "Filantropia" Municipal Hospital in Craiova, Romania, on November 26, 2002, for bilateral pain in the tarsometatarsal and carpometatarsal joints that had begun approximately four weeks before. After the clinical examination and paraclinical investigations, a diagnosis of unspecified arthritis is established and the adequate treatment is begun. Two months later, the patient returns to the clinic with bilateral knee pain and swelling. The results of laboratory tests indicate the persistence of anemia and of the inflammatory syndrome. The diagnosis of JIA is established. The evolution of the patient is unfavorable, both from a clinical point of view (a large number of articulations affected, a persistent rash, hepatomegaly) and a paraclinical one (increased acute phase reactants and radiological changes occurring two years after the onset of the illness).