Objectives: The aim of the current study is to determine the frequency of NOS3 27-bp VNTR in ADPKD patients and to investigate the role of NOS3 27-bp VNTR genotypes in the modification of progression of renal disease in ADPKD.Patients and Methods: The hypothesis was investigated by studying the South Indian population of 53 ADPKD patients and 94 unrelated healthy controls. The gene discussed is NOS3; the disease is autosomal dominant polycystic kidney disease.