Objectives: The assessment of renal function is particularly important in patients with spinal cord injury (SCI). Creatinine (Cr) is known to be unsuitable as a marker of renal function in SCI because of muscle wasting. Although cystatin C (cys-C) is more reliable than Cr, its expression may be affected by oxidative stress accompanying SCI. The aim of the study was to estimate the cys-C levels in SCI patients with normal functioning kidneys. The prooxidant/antioxidant state in plasma of the patients and controls was measured, and any correlations between these parameters and cys-C were determined.