We report two autopsy cases of Sjögren's syndrome associated with pulmonary hypertension. The pulmonary muscular arteries of both cases showed concentric fibrocellular intimal proliferation, medial hypertrophy, and plexiform lesions. To determine the significance and pathogenesis of this rare association, we carried out morphometric and immunofluorescent studies and reviewed the seven similar cases reported in the literature. Depositions of immunoglobulin G, Clq, C3c, C4, and C5 were observed in the pulmonary arterial walls of both of our cases. Morphometric studies revealed increased medial thickness to radius ratios and intimal thickness to radius ratios of the pulmonary muscular arteries in both cases. Previously reported patients were all female, and those cases were frequently associated with Raynaud's phenomenon. This report provides additional and convincing evidence for an association of Sjögren's syndrome and plexogenic pulmonary hypertension based on a detailed study of two cases and a review of the literature. The significance and pathogenesis of this association were examined, but not clarified. However, our studies add to the accumulating data suggesting a link between autoimmune diseases and chronic pulmonary hypertension.