Aim: to evaluate the functional results and clinical efficacy of adipose tissue-derived stem cells in stage II of knee osteoarthritis during a 12-month follow-up period. Materials and methods. 10 patients with stage II of knee osteoarthritis, 6 (60.0%) men and 4 (40.0%) women were examined, the mean age was 48.55±14.00 years. In 9 (90.0%) patients a unilateral knee osteoarthritis was established, in 1 (10.0%) — bilateral. Thus, the results of the examination of 11 knee joints were analyzed. Treatment of knee osteoarthritis was performed by intra-articular injection of adipose tissue-derived stem cells using Lipogems^® technology («Lipogems International SpA», Italy) according to the recommended technique. Clinical outcomes were assessed before treatment and 12 months after the procedure. The functional state of the knee joint was assessed using the Knee Іnjury and Osteoarthritis Outcome Score (KOOS). Statistical analysis was performed using «Microsoft Excel 2019» and «StatSoft STATISTICA 10». Results. In the remote period after the use of adipose tissue-derived stem cells in patients with stage II of knee osteoarthritis, positive dynamics was obtained in all categories of assessment of the functional state of the knee joints: «Symptoms» (p=0.00005), «Pain» (p=0.0002), «Function, everyday life» (p=0.00007), «Function, sports and leisure» (p=0.00006), «Quality of life» (p=0.00006). Conclusion. During the 12-month follow-up period, high clinical efficacy of adipose tissue-derived stem cells in stage II of knee osteoarthritis was demonstrated.