A comparison of function of individuals 1 year after total knee arthroplasty (TKA) with healthy control subjects (controls) meaningfully describes outcome in these patients. Perception of function measured by two questionnaires, the Lower Extremity Activity Profile (LEAP) and the Western Ontario McMaster Osteoarthritis Index (WOMAC), and walking and stair performance was compared between 29 patients, 1 year after TKA, and 40 controls. There was significantly greater perceived difficulty with function in patients with TKA than in controls. In TKA men, LEAP and WOMAC scores correlated respectively with self-paced walk speed (r= −.71 and −55) and stair performance time (r = 0.70 and 0.68). In TKA women, LEAP difficulty score correlated with self-paced walk speed (r = −.41) and stair performance time (r = 0.71). By 1 year, TKA subjects regained 80% of the function of controls. Perception of function after TKA can be measured by either questionnaire in men; howeverf the LEAP is the preferable questionnaire with women.