Introduction. Total knee replacement has become a standard planned intervention at specialized clinics. The study of surgical results is not as urgent as the follow up of the patients with concomitant pathology because various complications are most often registered in this group. Purpose: to evaluate the efficacy of total knee arthroplasty in patients with increased body mass index at early rehabilitation steps. Patients and methods. Open prospective comparative study included 75 patients with III–IV stages of gonarthrosis by Kellgren–Lawrence. Mean age of the patients made up 63.8±6.87 years. Main group included 48 patients with excessive body mass and alimentary-constitutional obesity of different degree, the control group — 27 patients with normal body mass index. The duration of intervention, volume of blood loss intraoperatively and drainages was assessed. Evaluation of clinical functional results was performed OKS, KSS and visual analog scale (VAS) before surgery, at discharge, 3 months and 1 year after surgical intervention. Results. In comparison to the patients with normal body mass index the patients from the main group showed slightly higher duration of the intervention and intraoperative blood loss — by 13.05% (p=0.027) and 12.8% (p=0.003), respectively. In the main group the severity of pain syndrome by VAS decreased from 90.4±14.4 to 9.6±0.4 mm (p=0.0001), evaluation of clinical functional results by KSS increased from 47.39±1.63 to 88.02±2.01 points, by OKS — from27.3±4.3 to 43.2±6.5 points (p=0.001). In the control group the severity of pain syndrome by VAS within 1 year follow up decreased from 86.2±2.4 to 3.8±0.7 mm (p=0.002) and clinical functional indices by KSS increased from 52.2±10.1 to 93.8±1.3 points (p=0.001), by OKS — from28.4±1.6 to 44.7±1.9 points (p=0,001). Conclusion. The study results demonstrate the high potentialities of arthroplasty in patients with alimentary obesity and confirm the necessity of its performance for the improvement of the patients’ future quality of life.