Low frequency dielectric spectroscopy (LFDS) is an analytical technique which has found considerable application in the study of pharmaceutical systems. In this article, an outline of the theoretical and practical aspects of the method will be given, as well as a discussion of the advantages and disadvantages of the technique. Examples will be given of how LFDS may be used in the analysis of pharmaceutical systems, including studies on solid dispersions, inter-batch variation, liposome suspensions and cyclodextrins.