Chronic kidney disease is the most important factor in predicting adverse short- and long-term outcomes after percutaneous coronary intervention. Most studies of cardiovascular outcomes have found that a break point for the development of radiocontrast nephropathy (RCN), later restenosis, recurrent myocardial infarction, congestive heart failure, and cardiovascular death, occurs below an estimated glomerular filtration rate (eGFR) of 60 mL/min/1.73 m², which roughly corresponds to a serum creatinine (Cr) of > 1.5 mg/dL in the general population. Renal dysfunction is accurately recognized by calculating the eGFR from the age, serum creatinine, gender, race, and weight, and not from the serum creatinine alone. The pathogenesis of RCN goes beyond serum Cr and involves a unique vascular pathobiology that interrelates both the renal and cardiovascular disease outcomes.