Aim To investigage the association of fibroblast growth factor 23 （FGF23） with carotid atherosclerosis in patients with moderate and advanced stage chronic kidney disease （CKD）. Methods Serum intact FGF23 levels in 120 patients with CKD stage 3 to 5 and 20 age and sex-matched healthy controls were measured by enzyme-linked immunosorbent assay （ELISA）. There were 30 non dialysis patients, 30 peritoneal dialysis patients and 60 hemodialysis patients. The difference between non dialysis group, peritoneal dialysis group and hemodialysis group was compared, too.The patients with moderate and advanced stage CKD were divided into atherosclerosis group and no atherosclerosis group, which clinical parameters and level of FGF23 were compared. The association between FGF23 and carotid atherosclerosis was studied. Results The incidence of carotid atherosclerosis in patients with moderate and advanced stage CKD was relatively high （59/120, 49.2%）. The levels of serum FGF23 in atherosclerosis group were significantly higher than no atherosclerosis group （P<0.01）. The serum levels of FGF23 in patients were significantly higher than those in the healthy controls （P<0.01）. The levels of FGF23 were higher in dialyzed patients than those in non-dialyzed patients （P<0.05）,