Screw fixation of the tibial component offers advantages in fixation in cementless total knee arthroplasty (TKA). In a group of 447 cementless TKA tibial components fixed without screws, 24% had partial undersurface radiolucent lines and 3% had complete radiolucent lines. Both of these parameters were significantly decreased (p < 0.01) when screws were used. In a group of 1442 cementless tibial trays fixed with screws, 4% had partial and 0.1% had complete radiolucent lines. Cyst formation around smooth pegs was also more common in trays fixed without screws. Two of the 5758 screws inserted in 1442 trays developed nonprogressive radiolucent lines, but no case of major osteolysis has been seen. Although screw fixation of cementless tibial components appears to improve the metal-bone interface, the potential for longterm complications still exists. The use of screws should be reserved for difficult fixation problems.