Dissolution stability (i.e., retention of the dissolution characteristics of a solid oral dosage form from the time of manufacture up to its expiration date) is a critical parameter from the standpoint of quality control, regulatory compliance, and impact on the bioavailability of the product. Significant changes in the in vitro release profiles of a drug product during storage may alter its bioavailability. Factors that affect the dissolution stability of a product during aging include formulation components (active drug, excipients, and coating materials), processing factors, storage conditions, and packaging. The role of each of these factors in promoting changes in dissolution in both immediate-release and modified-release products is dependent on the product and has to be evaluated on a case-by-case basis. Although data obtained under accelerated conditions of storage are not useful in predicting the dissolution shelf-life of the product under ambient conditions, they are of value in assessing the "ruggedness" of the product and its ability to withstand the varied climatic conditions during transport, shipping, and storage. The clinical significance of alterations in the in vitro dissolution profiles that may occur during aging and strategies to avert and counteract such changes are discussed in the article.