We describe a euthyroid patient who presented with a goiter that continued to enlarge despite levothyroxine administration. Three fine-needle aspirations for cytology were nondiagnostic. An open biopsy was complicated by bleeding from the surgical site. Primary systemic amyloidosis was diagnosed on the basis of the goiter histology, bone marrow aspirate, and urine immunoelectrophoresis. The patient received melphalan and steroid treatment and survived for an additional 16 months. This period was complicated by congestive heart failure, generalized seizures, and upper gastrointestinal bleeding. Our case illustrates the difficulties in making the diagnosis and in treatment of primary systemic amyloidosis.