We describe a small case series with severe metallosis after revision total knee arthroplasty (TKA) due to metal-backed patellar component failure. Metallosis is a rare complication after TKA, which may cause systemic and local symptoms. In our cases, diagnosis of metallosis was supported by radiographic imaging and aseptic aspiration. Two of our 3 cases were successfully revised; in the remaining case surgery was not desired because of her poor general condition. Based on these cases, we recommend performing regular checkups in case of a metal-backed patellar component to detect metallosis in an early stage, to prevent extensive revision surgery. Moreover, we recommend applying a low threshold to revise a metalbacked patellar component because of the severe consequences of metallosis that might occur.