The origins, chemical differences, and methods of assay of various digitalis preparations are summarized. Recent studies in the distribution and fate of these drugs are reviewed. The general pharmacologic properties are discussed with special reference to the relation of digitalis action to cations. Quantitative differences in the biologic action of the various preparations are described. The indications and contraindications for digitalis in a wide variety of disorders are considered. Techniques of digitalis administration, and the manifestations and management of toxicity are discussed.