Nephronophthisis (NPH), an autosomal recessive cystic disease of the kidney, is the most common genetic cause of end-stage renal disease (ESRD) in the first three decades of life. Juvenile nephronophthisis can be associated with extrarenal organ involvement. The appropriate diagnosis of NPH is important not only for anticipating progressive renal failure but also for the implications on genetic counseling. We have studied 15 patients with NPH (4 of them had extrarenal manifestations). All patients were found to have a significant reduction of glomerular filtration rate at presentation. The most useful imaging technique in NPH is ultrasonography. Normal renal size and cysts were present in the majority of cases but cysts appear late in the course of the disease. So the absence of cysts does not rule out the diagnosis of NPH. The characteristic histopathologic triad of NPH is present in all biopsied cases.