CKD is important, because of not only the breaking increase of dialysis patients, but also the increase of risk to cardiovascular disease especially myocardial infarction. Definition of CKD is consisted with 2 criteria, one is abnormal renal function or morphology especially proteinuria. Second is eGFR less than 60 mL/min calculated by the equation using serum creatinine. CKD is classified by eGFR from stage 1 to stage 5. stage 1 is eGFR being more than 90 mL/min and with other renal abnormality such as proteinuria. In stage 2, eGFR is between 60-90 mL/min, in stage 3, 30-60 mL/min, in stage 4, 15-30 mL/min, and in stage 5, under 15 mL/min, respectively. There are many issues including this definition and classification of CKD, but still CKD is important for evaluation, prevention, and treatment, in terms of improving QOL of peoples.