Impairment of renal function beginning from subclinical stages is independent risk factor of development of cardiovascular diseases and cardiovascular death. Cystatin C is considered in recent years as an alternative marker of functional state of the kidney and risk of development of cardiovascular diseases. Cystatin C is a protease inhibiting protein with low molecular mass which is characterized by free glomerular filtration and is not subjected to tubular secretion. Formulas are elaborated for calculation glomerular filtration rate basing on cystatin C level. In this review we consider potential advantages of cystatin C for assessment of early impairment of renal function. We also present data on interrelation between cystatin C, metabolic parameters, and markers of target organs damage, on prognostic value of cystatin C in various populations of patients.