In recent years, the worldwide, the attention has been focused on the development of new drug products with controlled delivery. The reason for this new tendency is relatively low cost and time required to development this kind of product as compared to a new drug. In this sense, the osmotic systems, controlled delivery drug products, have been chosen for the present review to illustrate their physicochemical principles that govern their formulation. Different types of oral osmotic systems and their applications are also discussed. Finally, some studies related to this subject were reviewed. Because of their advantages and strong market potential, the future of osmotic systems seems so good.