Background. Sarcopenia is the main factor in the pathophysiology of frailty syndrome. There is a closer relationship between frailty and functional performance than with muscle mass. Obesity (due to mechanical and physiological factors), acts synergistically with sarcopenia in relation to frailty. The combination of obesity and sarcopenia (i.e. sarcopenic obesity) is associated with a higher incidence of frailty. Aim: to evaluate the relationship between sarcopenia (according to the EWGSOP2 classification) and obesity diagnosed by body mass index (BMI) >30 kg/m2 and by a high proportion of fat mass (FM) according to bioimpedance measurement (BIA) with frailty syndrome. Materials and methods. The study included 371 polymorbid patients (mean age 78.15±7.22 years). Anamnesis, complaints, bad habits (alcohol consumption), anthropometric indicators (height, weight, BMI) were collected from all participants, muscle strength was studied using a handgrip dynamometer (DC-50, Russia), walking speed according to the standard method. The study of body composition was carried out on the ABC-02 device («MEDASS», Russia). The presence of frailty syndrome was assessed according to the questionnaire "Age is not a hindrance". Results. Frailty was diagnosed in 38.5% (n=143) of patients, pre-frailty – in 51.5% (n=190); 10% (n = 37) were robust. Sarcopenia was found in 19.8% (n = 73) of participants. The prevalence of obesity by BMI was 21.8% (n = 81), while the prevalence of obesity by FM, determined using BIA, was three times higher - 67.7% (n = 251). Among the participants with sarcopenia, 72.6% (n = 53) were obese by FM and only 8.2% (n = 6) were obese by BMI. In participants with sarcopenia, 91.8% (n=67) were not obese by BMI and 27.4% (n=20) were obese by FM. Logistic regression analysis showed a reliable association of frailty syndrome with sarcopenic obesity according to FM, both without adjustments (p