As DM, HTN and comorbidities are increasing, ESRD patient also increasing considerably. For ESRD patient, AV fistula is one of suitable modality to maintain hemodialysis than AVF or central vein catheter. However, vascular problem or AV fistula immaturity accounts for 20% to 54% of AVF failure. Multiple factors affecting AVF maturation, such as age, DM, lipid profiles, smoking, obesity, serum albumin level, Vein diameter in ESRD patient. There are rare studies associated postoperative follow-up AV fistula data and numeric data analysis have not be done. So, we assumed that prior cephalic vein diameter and after 6weeks cephalic vein increasing ratio is associated with maturity.   We studied 2014.01.01-2019.12.31 total 339 patient who have done innate AV fistula     We analyze 6month after AV fistula via duplex ultra sonograph factors and other key laboratory data that affecting AV fistula immaturity. Vein diameter is one of the important factors in AVF maturity.  we measure cephalic vein diameter (after 6month)/ cephalic vein(pre-operative) ratio  There is no difference between  cephalic vein maturity diameter ratio 0.211(immature AVF), 0.212(mature AVF)  Other crucial AVF maturity factors will be discussed in here, it is important innate artery or vein status most important and artery calcification is most affecting immaturity in our center data. nephrologist and doctors should ensure preventive arm saving beforehand in chronic kidney disease who are preparing  hemodialysis