<p class="abstract"><strong>Background:</strong> The present study was carried out with the objective to assess the influence of morbid obesity on the outcome after TKR and with the aim to compare the outcome following TKR in a consecutive series of morbidly obese patients (BMI >40 kg/m<sup>2</sup>), and matched it with group of non-obese patients (BMI <30 kg/m<sup>2</sup>).</p><p class="abstract"><strong>Methods:</strong> The study period planned was of two years. The totals of 100 patients undergoing total knee replacement were selected for the study period. On the basis of body mass index inclusion criteria for the two groups were decided. Of the total 100 patients, they were divided into two groups. One group 1 consisted of obese patients with total of 50 patients and group 2 consisted of non-obese patient with total of 50 patients.<strong></strong></p><p class="abstract"><strong>Results:</strong> At the end of two years when the data was compared with the preoperative assessment, it was found to significantly better where value of p was <0.001. However when the comparison was done between the two groups, it was found that scores were lower in the group 1 patients which included the obese patients.</p><p><strong>Conclusions:</strong> Total knee arthroplasty is a safe and efficacious operation in obese patients with no significantly greater risk of complications. However, post-operative clinical scores and absolute improvement in the scores are statistically superior in non-obese patients at one year follow-up. Obese patients should be started on weight loss programs and counselled about possible inferior results for total knee replacement. </p>