Major progress has been achieved in autosomal dominant polycystic kidney disease in the last 30 years; Progress in imaging procedures has been decisive for diagnosis (by ultasonography), management of kidney and liver complications (by CT scan), and investigation and sometimes management of intracranial aneurysms (by MRI-angiography and endovascular treatment procedures). On the other hand, progress in molecular genetics has led to the identification of PKD1 and PDK2 genes, and their respective gene products, polycystin 1 and 2. A two-hit model for cyst formation has recently been put forward. The link between the gene defects and cyst fluid formation and progression is still unknown. In addition, cystic and non-cystic lesions coexist in the disease, underlining that the primary molecular defect is located upstream of the mechanism of cyst formation.