Present book provides detailed information on osmotic drug-delivery systems. Development and characterization aspects of elementary osmotic pump tablets are explained this book. Such delivery systems are based on the principle of osmosis. Osmosis refers to the process of movement of solvent from lower concentration of solute towards higher concentration of solute across a semi-permeable membrane. These delivery systems are also ideal for zero order drug release. This book may be helpful for U.G. and P.G. students for their project work.