A prospective study was performed to compare the alignment after total knee arthroplasty (TKA) using two different alignment systems: an intramedullary system versus an extramedullary system. These two systems were alternately used to make the distal femoral resection in 50 patients. There was little difference between the two systems in achieving appropriate valgus of the distal femoral cut and a correct angle of tibiofemoral valgus.