Abstract Funding Acknowledgements Type of funding sources: None. Comorbidity increases with age, including the presence of cardiovascular disease, chronic kidney disease (CKD) and obstructive sleep apnea (OSA). OSA is considered as a risk factor for the progression of CKD. The aim of this study was to investigate сomorbidity and quality of life in older patients with chronic cardiorenal syndrome and obstructive sleep apnea. Materials and methods 80 older patients with stable cardiovascular disease and CKD (43 males, mean age was 67.6 ± 6.1 years) were studied. CKD was diagnosed and classified according to the KDIGO guidelines (2012). OSA was observed according to Clinical Guidelines for Obstructive Sleep Apnea and Insomnia (U.S., 2020). Berlin Questionnaire and Epworth Sleepiness Scale, cardiorespiratory monitoring for screening and diagnosis of OSA were used. Charlson comorbidity index (CCI) was estimated. The patients" quality of life (EQ-5D-5L), the presence of anxiety and depression (Hospital Anxiety and Depression Scale), psychological defense mechanisms were assessed. Results Chronic kidney disease was observed in 48 (60%) patientswith stable cardiovascular disease. OSA was first diagnosed in 31 (64.5%) older patients with CKD. Рatients with CKD had a high comorbidity independently of OSA: CCI was 8 (7; 8) points in patients with OSAS and 7 (7; 8) points in patients without OSAS (p = 0.51). There was a direct relationship between CKD and the severity of daytime sleepiness (r = 0.30, p = 0.02), as well as complaints about the quality of sleep (r = 0.31, p = 0.01) in patients with CKD. Severity of anxiety and depressive reactions, disturbance of habitual activity, increased pain and discomfort, decrease QOL index (EQ-5D-5L) in the presence of disturbed sleep quality and daytime sleepiness were observed. With a Older patients with CKD and decrease in the quality of sleep less commonly used mature mechanisms of psychological defense, such as «рrojection» (r = -0.39, p = 0.04) and «rationalization» (r = -0.41, p = 0.03). There was association between the severity of sleep disorders and the tension of the primitive mechanism of psychological defense «regression» (r = 0.41, p = 0.008), which contributes to the impairment of adaptation in older patients with CKD. Conclusion Older patients with CKD and OSA have a high comorbidity, including cardiovascular comorbidity. There were no differences in the structure of comorbidity in older patients with chronic cardiorenal syndrome, depending on the presence of OSA. Sleep impairment, daytime sleepiness were associated with the severity of anxiety and depression, a decrease in the quality of life, and maladjustment.