The aim of this study was to evaluate the outcome of joint arthroplasty in obese and non-obese patients. We reviewed 2,026 consecutive primary total hip and 535 primary total knee arthroplasties performed for osteoarthritis. Patients were separated into two groups according to their body mass index (BMI): non-obese (BMI < 30) and obese (BMI ≥ 30). Their survivorships were compared. Case controlled studies were performed with 134 hip and 50 knee arthroplasties in obese patients. Each was matched individually with a control and their outcome compared. Log rank tests for equality of survival showed no difference in the survival for hip and knee arthroplasty at 11 and ten years, respectively. The obese group had significantly lower postoperative hip and knee scores at latest follow-up, especially in the range of motion. Overall patient satisfaction scores were comparable. There were no significant differences in the radiographic analysis of both hip and knee implants. Revision was used as an end point for the survival analysis. Functional scores (Harris hip score and Hospital for Special Surgery knee score), satisfaction for surgery and radiographic features were used as outcome measures for comparison. The mid-term survival of total hip and knee arthroplasty is not adversely affected by obesity. Despite lower clinical scores, the obese patients were satisfied with the results of their surgery and have an equivalent mid-term survival rate. It would be unreasonable to deny patients arthroplasty surgery purely on the basis of a BMI indicating obesity.