Aquaporin-2 (AQP-2) is known to be expressed in the renal collecting duct cells and participates in urinary concentration in response to vasopressin. No information on aquaporin genetic variations in chronic kidney disease (CKD) is available to date. Blood samples from 259 patients with CKD and 106 ethnically, age and sex-matched healthy controls were collected and genomic DNA was extracted. AQP-2 -667 genotype was assessed by PCR, followed by restriction fragment length polymorphism analysis. 79 (30.5%) patients had the AQP-2 -667 wild-type A/A, 123 (47.5%) were heterozygous for the G allele and 57 (22.0%) patients showed homozygosity. There were no significant differences in genotype and allele frequencies between the patients group and the group of healthy controls. After subclassification of CKD according to underlying disease, no significant differences were observed between any of the groups and the control group. Genotype and allele frequencies of the AQP-2 gene polymorphism (rs3759126) of hypertensive patients in pre-end stage renal disease (pre-ESRD) did not show noticeable difference compared with normal blood pressure patients in pre-ESRD. No correlation was found to exist between the AQP-2 gene polymorphism (rs3759126) and serum electrolyte levels in pre-ESRD. Our data indicate that no association exists between the -667 AQP-2 A/G polymorphism and susceptibility to CKD or its clinical course.