Uromodulin in physiological conditions is the most abundant urinary protein. This protein is exclusively produced in the kidney by cells in the thick ascending limb of the loop of Henle and the early distal tubule. This creates the opportunity for the study which may extend uromodulin use in patients with chronic kidney disease (CKD) in various stages of progression as the serum marker associated with renal tubules dysfunction. The aims of the study were to demonstrate the correlations between serum uromodulin and commonly used renal markers and various measures of glomerular filtration rate in patients with chronic kidney disease (CKD). Additional intention was check if there was any correlation between serum uromodulin and markers of calcium‑phosphate and bone metabolism in those patients. This study included 119 patients with CKD stages 3 to 5. A control group consisted of 32 subjects. Kidney function markers, calcium‑phosphate and bone metabolism markers were determined in all studied patients. The conducted analyses demonstrated statistically significant differences between the average concentration of serum uromodulin in the study groups and in the control group (control group 188.2+–72.5 ng/ml, stage 3 70.9+–40.0 ng/ml, stage 4 37.3+–15.7 ng/ml, stage 5 18.7+–14.1 ng/ml [p = 0.000]). The results of the research have shown clearly statistically significant correlations between serum uromodulin concentration and measures of glomerular filtration rate expressed as equations CKD‑EPI Cystatin C and CKD‑EPI Creatinine‑Cystatin C in the analyzed groups with CKD stages 3 to 5. The authors demonstrated statistically significant correlations between serum uromodulin concentration and markers of bone metabolism in stage 5 of CKD. Serum uromodulin concentration may be an additional marker that enriches the assessment of kidney functioning in various stages of progression of CKD. Low serum uromodulin concentration may suggest disorder of bone metabolism in patients treated with dialysis.