Introduction. In the last years, the global prevalence of the moderate severe renal dysfunction has gradually increased to an epidemic state. The risk of chronic kidney disease occurrence in heart failure ( is not well establish ed, but kidney dysfunction is very often encountered in HF patients and is associated with a poor prognosis. Thyroid hormone, also, has been identified as a risk factor for the heart disease progression and development. Aim of the study. To investigate whe ther thyroid function is associated with chronic kidney disease in heart failure patients. Materials and methods. This observational cohort study included 25 patients with reduced ejection fraction heart failure CKD. Routine biochemistry, including Cystein e C, thyroid stimulating hormone(TSH) and proteinuria were measured. Glomerular filtration rate ( was estimated by the CKD EPI CYSTETIN C based formula adjusted for Body Surface Area. We divided patients into two groups according to estimated GFR: ≥60m l/min (CKD stages I II KDOQI); and <60ml/min(CKD stages III V KDOQI). Results. Among 26 adult participants, 15 had moderate to severe decrease in eGFR<60 ml/min with a mean TSH level of 7.4±3.28 UN/ml(p<0.05); Cystetine C of 1.15±0.07 mg/L; mean ejection f raction ( of 43.4±2.84% level; uric acid level 446.2±81.27mmol/L; total cholesterol 7.95±3.37 mmol/L; triglycerides 2.19 mmol/L and 0.12 g/l proteins in urine. 11 subjects had elevated, normal or mild decrease in eGFR≥60 ml/min; a mean TSH level of 2. 2±0.65 UN/ml (p< Cystetine C of 1.74±0.13 mg/L; mean ejection fraction(EF) of 42±2.77%; uric acid level 235.5±113.5 mmol/L total cholesterol 7.95±3.37 mmol/L; triglycerides 2.19 mmol/L, and 0.07 g/l proteins in urine. Compared with participants wit h an estimated GFR ≥60 ml/min, those with estimated GFR <60 ml/min had an increased rate of subclinical primary hypothyroidism, higher levels of uric acid, total cholesterol and triglycerides. Conclusions. Our results suggest that subclinical hypothyroidis m is associated not only with heart failure but also with CKD, and may be considered as a novel risk factor of reduced renal function. Further studies are needed to better understand the causal implications of hypothyroidism in CKD patients.