IgG4-related disease is a newly recognized fibroinflammatory condition characterized by tumefactive lesions, a dense lym-phoplasmacytic infiltrate rich in IgG4-positive plasma cells, storiform fibrosis, and, often but not always, elevated serum IgG4 concentrations. The disease can either be localized to one or two organs, or be present with diffuse multi-organ disease. In the thorax, lesions associated with IgG4-related disease have been described in the lung parenchyma, airways and pleura, as well as the mediastinum. We report a case of IgG4-related disease presenting as massive pleural effusion and thrombophlebitis. A 48-year-old man was admitted to our hospital complaining of fever, chills, sweating, and dyspnea. He has a history of admission for evaluation and management of suggested deep neck infection with small amount of left pleural effusion. On physical examination, he showed generalized edematous appearance with venous engorgement of neck and upper chest. Chest X-ray and Chest CT showed thrombophlebitis at left innominate vein, subclavian vein and left internal jugular vein and enlarged lymph node at left neck and axillar area with both pleural effusion and ascites. Pleural fluid analysis showed lymphocyte predominant exudates nature. Pleural biopsy showed chronic inflammation with lymphoplasmacytic infiltration and fibrosis. The ratio of IgG4-positive to IgG-positive plasma cells in specimen was 23%. Serum IgG4 level was 248 mg/dL. He showed symptomatic and radiographic improvement after systemic steroid therapy with anticoagulation.