Presently, 6 cases of IgG4-related pleuritis have been reported. We encountered a patient who developed chylothorax due to IgG4-related disease. To our knowledge, such patients have not been reported. This patient developed right-sided chylothorax and left-sided non-chylothorax lymphocyte-predominant pleuritis. Elevated serum and pleural IgG4 concentrations and histopathological analysis of pleural biopsy confirmed the diagnosis of IgG4-related pleuritis. Left-sided pleuritis improved with corticosteroid therapy, but right-sided chylothorax persists. IgG4-related disease can be one cause of chylothorax.