Giant cell (temporal) arteritis (GCA) may be a cause of fever of unknown origin (FUO) in elderly patients. The development of secondary (reactive) amyloidosis is an unusual complication of the disease, we describe a 65-year-old male patient who was hospitalized in our hospital with FUO and was diagnosed as having GCA 5 years later. At that time, he also had a nephrotic syndrome and secondary amyloidosis (AA-type). He died due to end-stage renal failure. The probable explanation for the development of this rare complication might be the late diagnosis of this chronic inflammatory disease, which was left untreated for a long period of time.