The aim of this study was to identify mutations in three different genes, the arginine-vasopressin-neurophysin II (AVP-NPII) gene, the arginine-vasopressin receptor 2 (AVPR2) gene, and the vasopressin-sensitive water channel aquaporin-2 (AQP2) gene in Turkish patients affected by central diabetes insipidus or nephrogenic diabetes insipidus. This study included 15 patients from unrelated families. Prospective clinical data were collected for all patients including the patients underwent a water deprivation-desmopressin test. The coding regions of the AVPR2, AQP2, and AVP-NPII genes were amplified by polymerase chain reaction and submitted to direct sequence analysis. Of the 15 patients with diabetes insipidus referred to Gulhane Military Medical Academy, Department of Endocrinology and Metabolism, eight patients have AVPR2 mutations, five patients have AQP2 mutations and two patients have AVP-NPII mutations. Of the patients, which have AVPR2 mutations, one is compound heterozygous for AVPR2 gene. Seven of these mutations are novel. Comparison of the clinical outcomes of these mutations may facilitate in understanding the functions of AVP-NPII, AQP2, and AVPR2 genes in future studies.