Four cases with cardiac involvement in patients suffering from systemic outset of juvenile rheumatoid arthritis are reported. The cases were chosen out of 83 juvenile rheumatoid arthritis patients studied from 1975 to 1988. They developed respectively myopericarditis (case 1), myocarditis (case 2), endopericarditis (case 3), myopericarditis (case 4). The drug employed in the acute disease phase was exclusively prednisone; in all subjects the acute inflammatory stage resolved.