Polysaccharide rich gums and mucilages are produced by different natural sources such as plants, animals and microbial organisms to fulfil structural and physiological functions. Their diverse structural compositions with a broad range of physicochemical properties make them useful for inclusion in dosage forms for different purposes such as to improve manufacturing processes and/or to facilitate drug delivery. A number of natural gums and mucilages have been investigated for inclusion in pharmaceutical formulations for a variety of reasons. The search for new excipients continues to be an active topic in dosage form design and drug delivery research. The aim of this review article is to give an overview of the chemical nature of natural gums and mucilages and to discuss their applications in the formulation of pharmaceutical dosage forms. Special emphasis will be placed on the use of gums and mucilages in novel drug delivery systems, such as modified release dosage forms and delivery systems that target specific sites of delivery.