Recent progress in studying epithelia in culture indicates that techniques already available and applied to naturally occurring epithelia can be applied effectively to cultured epithelia. Studies using this approach are summarized as well as new information the studies have yielded regarding the mechanism of action of aldosterone and the regulation of expression of the sodium-coupled hexose transporter. In addition, special features of cultured epithelia should lead to new approaches to understanding epithelial biology as well as epithelial transport.