Colon-specific drug delivery systems offer several potential therapeutic advantages. In a number of colonic diseases such as colorectal cancer, Crohn's disease and spastic colon, it has been shown that local is more effective than systemic delivery. Colonic drug delivery can be achieved by oral or by rectal administration. Rectal delivery forms (suppositories and enemas) are not always effective because a high variability is observed in the distribution of drugs administered by this route. Therefore, oral route is preferred. Absorption and degradation of the active ingredient in the upper part of the gastrointestinal tract (GIT) is the major obstacle with the delivery of drugs by oral route and must be overcome for successful colonic drug delivery. Drugs for which the colon is a potential absorption site (e.g. peptides and proteins) can be delivered to this region for subsequent systemic absorption. The digestive enzymes of the GIT generally degrade these agents. However, these enzymes are present in significantly lower amounts in the colon compared with the upper portion of the GIT. Colon-specific drug delivery has been attempted in a number of ways that primarily seek to exploit the changes in the physiological parameters along the GIT. These approaches include the use of prodrugs, pH-sensitive polymers, bacterial degradable polymers, hydrogels and matrices, as well as multicoating time-dependent delivery systems. The use of these strategies to target drug delivery to the colon is addressed in detail.