Titanium alloy has been widely used as material for total knee arthroplasty(TKA). However, titanium alloy has frequently been reported as causing black staining of the periprosthetic tissues as a result of debries from metallic wear and tissue reaction. We report six cases of failed TKA in five patients, in which the tibial tray and/or metal backed patellar components were composed of titanium alloy. Wear, breakage or separation of the ultra-high molecular weight polyethylene of tibial insert and/or patellar component, which allowed metal-on-metal friction and aggravated the production of metal wear debries, were observed in all cases. The average time from primary operation to revision was 5 year and 3 months (range, 9 months to 8 year and 8 months). In all cases, patients showed painful swelling of knee jont and radiopaque periarticular deposits on radiogrphs. Most of radiographs showed abnormal position of the metallic components and metal line sign. Histology of synovium showed abundant titanium particles lying free and within histiocytes, and polyethylene and cement particles with foreign-body type giant cell reaction. The synovial lining showed a preliferative reaction and abundant fibrosis was noted. On polarizing briefringent. Elemental analysis of metal particles on histologic section, using energy dispersive X-ray spectrophotometer (EDS ; EDAX PV9900) unit attached to a transmission electron microscope, detected the titanium peak. Radiopaque metallic densitien in the painful knee after TKA are highly suggestive findings of titanium reaction. Tissue reaction in response to the metal wear debries from titanium prosthesis may have contributed to the early failure of these implants.