We report this case of secondary amyloidosis associated with Castleman's disease. A 51-year-old man presented with systemic symptoms of generalized weakness, fatigue, unintended weight loss, anorexia and progressively worsening abdominal distension. On examination he was found to have an indurated right-sided submandibular mass and tense ascites. He was found to have multiorgan dysfunction with deranged liver function tests and renal failure. Ascitic fluid analysis revealed evidence of spontaneous bacterial peritonitis. Biopsy of the submandibular mass revealed angiofollicular lymph node hyperplasia consistent with a diagnosis of Castleman's disease. A subsequent liver biopsy showed extensive deposition of amyloid protein. Bone marrow biopsy also showed the presence of amyloid and increased kappa light chain-restricted plasma cells. The patient was not considered a candidate for chemotherapy or solid organ transplantation in view of active sepsis and poor physical condition. Secondary systemic amyloidosis complicating Castleman's disease is very rare. Untreated secondary systemic amyloidosis often has a rapidly fatal course, such as seen in our patient.