In order to determine the prevalence of inflammatory rheumatic diseases in an urban secondary school student population, a questionnaire dealing with past or present joint, tendon, axial, gastrointestinal, ocular and dermatological symptoms was completed by 2,990 students of secondary schools in Antwerp and Ghent. The parents were asked to complete a questionnaire regarding the family medical history. From these 2,990 students, 524 were selected for further investigation by a rheumatology resident, who checked the answers to the first questionnaire and performed a clinical examination. Forty-one adolescents with a presumptive history or present symptoms of inflammatory rheumatic diseases were retained. These students were examined by the medial staff of the rheumatology department; if necessary, a complementary biochemical and radiological examination was performed. Five cases of definite juvenile chronic arthritis (JCA) (with polyarticular onset in 1 case and late pauciarticular onset in 4 cases) and 4 cases of presumptive late pauciarticular onset JCA were detected, resulting in a prevalence of 167 per 100,000 for definite JCA and of 301 per 100,000 for possible JCA. This prevalence rate is higher than that generally described. This method of investigation effectively allows the detection of milder and spontaneously remitting cases of JCA. It further enabled us to definite case and 4 presumptive cases of various previously undiagnosed forms of JCA.