Purpose: To describe a case of Erdheim-Chester disease with bilateral orbital involvement.Methods: A 43-year-old female with bilateral proptosis was presented. Its clinical features, image findings, pathological character and therapeutic effect were evaluated. Results: CT demonstrated bilateral, diffuse orbital mass. Histopathologic assessment revealed a diffuse xanthogranulomatous process with clusters of lipidladen histocytes. Numerous Touton giant cells were scattered throughout the lesion.Renal and heart failure happened during a 6-year follow-up period. Long bones roentgenogram demonstrated diffuse symmetrical sclerosis with extensive, lytic lesions. Systemic administration of corticosteroids, chemotherapy, immunoglobulin and traditional Chinese medicine showed good therapeutic result.Conclusions: An administration of systemic corticosteroids, chemotherapy, immuno-globin and traditional Chinese medicine can control Erdheim-Chester disease. Further exploration of its pathogenesis Its clinical features, image findings, pathological character and therapeutic effect were expressed as a result of the diagnosis of Erdheim-Chester disease with bilateral orbital involvement. Methods: A 43-year-old female with bilateral proptosis was presented. bilateral, diffuse orbital mass. Histopathologic assessment revealed a diffuse xanthogranulomatous process with clusters of lipidladen histocytes. Numerous Touton giant cells were scattered throughout the lesion. Renal and heart failure happened during a 6-year follow-up period. Long bones roentgenogram demonstrated diffuse symmetrical Systemic administration of corticosteroids, chemotherapy, immunoglobulin and traditional Chinese medicine showed good therapeutic result. Conclusions: An administration of systemic corticosteroids, chemotherapy, immuno-globin and traditional Chinese medicine can control Erdheim-Chester disease. Further exploration o f its pathogenesis