Background. Patients with chronic cardiorenal syndrome type 2 (T2-CRS) who qualify for resynchronization therapy (CRT) are exposed perioperatively to potentially nephrotoxic factors including contrast agents and blood loss. Methods. The objective of this prospective interventional study was to assess the effects of CRT on renal function in patients with T2-CRS within the first 48 hours following implantation. Initially, 76 patients (15% female; aged 69 ± 9.56 years) with heart failure (New York Heart Association classes II–IV), ejection fraction ≤ 35%, and QRS > 130 ms were included in the study. During CRT implantation, a nonionic contrast agent (72.2 ± 44.9 mL) was administered. Prior to and 48 hours following implantation, renal function was evaluated using the following serum biomarkers: creatinine (sCr), estimated glomerular filtration rate (using the Chronic Kidney Disease Epidemiology Collaboration equation [eGFRCKD-EPI]), and the electrolyte and urine biomarkers albumin (uAlb), albumin/creatinine ratio (UACR), and neutrophil gelatinase-associated lipocalin (uNGAL). Results. Before CRT, patients classified as NYHA class III or IV had higher uNGAL levels in comparison to uNGAL levels after CRT (43.63 ± 60.02 versus 16.63 ± 18.19; p=0.041). After CRT implantation, uAlb, UACR, and potassium levels were reduced (p<0.05), and uNGAL, sCr, and eGFRCKD-EPI were unchanged. The contrast medium volume did not correlate with the test biomarkers (p>0.05). Conclusions. In patients with T2-CRS, uNGAL is a biomarker of kidney injury that correlates with the NYHA classes. A stable uNGAL value before and after CRT implantation confirms the lack of risk of contrast-induced nephropathy. Reduced albuminuria and blood potassium are biomarkers of improving T2-CRS in the early post-CRT period.