Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common human hereditary disorder characteristic of development of bilateral multiple fluid-filled kidney cysts. Accumulated evidence has suggested that primary cilium of renal epithelial cell plays a key role in cystogenesis. In this article we will give an overview on the basic information about polycystic kidney disease (PKD) and summarize the recent progresses in studies of regulation of polycystin-1 and -2 trafficking to cilia. We will also discuss the possible role of trafficking defects of polycystins on the pathogenesis of ADPKD.