We describe a 16-year-old girl with systemic-onset juvenile arthritis who presented with pulmonary hypertension, without evidence of pleural or parenchymal involvement of the lung, pulmonary vasculitis, or immune deposition in the pulmonary vasculature. Pleuropulmonary involvement occurs occasionally in juvenile arthritis, but primary pulmonary hypertension has not, to our knowledge, been previously reported. Histocompatibility typing showed positivity for HLA-DR3 and DRw52, both of which are associated with idiopathic pulmonary hypertension in children, and with pulmonary hypertension among patients with systemic sclerosis. Treatment with cyclosporine and corticosteroids resulted in a marked improvement in the clinical findings and pulmonary function in our patient.