Hydrodynamic forces, including fluid shear stress, circumferential stretch and drag/torque on apical cilia, regulate ion transport in the cortical collecting duct (CCD) of the kidney. Studies aimed at examining pathways and regulation of transepithelial transport in this nephron segment are largely limited to experiments in 2D cell culture monolayers, while renal tubular epithelia grown in their native 3D geometry provide a more physiologically relevant environment. We are developing and characterizing a novel in vitro 3D microphysiological kidney-on-a-chip model that recapitulates the in vivo geometry of the CCD that promises to provide a relevant model for studying tubular ion transport physiology and addressing a variety of clinically important questions.