This paper introduces expert systems and considers the advantages and disadvantages of their use in pharmacy. It describes how the future pharmacist is likely to be assisted by an expert system for diagnosis and patient management, and details a pharmacy system which accesses doctors' records and prescription databases, relieving the pharmacist of much clerical work and even some clinical activities. The provision of expert systems for public use and the potential for computer aided learning is also discussed. However, the legal aspects of expert system use remain to be clarified. Two prototype systems being developed at King'e College, London, are described.