Dynamic mechanical thermal analysis (DMTA) is an analytical technique which involves the measurement of the rheological properties of a sample over a range of temperatures. The theoretical and practical principles of the technique are outlined, including a description of dynamic mechanical measurements and the types of measuring mode currently available. A series of examples are given in which DMTA has been used to characterise the rheological properties and glass transition behaviour of materials of pharmaceutical interest. These include synthetic polymeric samples such as film coats, gels such as pectin-water systems, polysaccharides such as hydroxypropyl methylcellulose and proteinaceous materials such as elastin. A discussion of how the technique could be used in the future to characterise pharmaceutical samples is given.