In the 1st part of this review dealing with FGF-23 its composition, mode of action, and regulatory mechanisms of its secretion were described. In the 2nd part of this review, regulatory activity in the calcium-phosphate homeo-stasis in different stages of chronic kidney disease (CKD) including dialyzed patients, subjects after parathyreoidectomy and patients after kidney transplantation were characterized. The aim of this part was to analyze the relationship between FGF-23 and left ventricular hypertrophy, vascular calcification and increased morbidity and mortality in patients with CKD. The current knowledge on FGF-23 has lead to suspect that in the nearest future it may serve as sensitive marker of early calcium-phosphate disturbances in patients with CKD.