Obesity has been considered an adverse influence on the outcome of total knee arthroplasty (TKA), and overweight patients often are advised against having a TKA. The role of body weight has not been shown conclusively using objective outcome measures. A group of 180 patients undergoing primary TKA performed by a single surgeon for osteoarthritis was studied prospectively. Their baseline health status and knee scores were recorded, and changes in these measures were studied at 3 and 12 months after surgery. The Nottingham Health Profile was used to assess health status, and the Knee Society score was used to assess clinical outcome. Body mass index was used as a measure of obesity. We found that body weight did not influence adversely the outcome of TKA in the short-term.