Case registers have very little to do with computers or any other form of mechanical calculating machine. To write an article on case registers which concentrated on information technology would be as logical as an article on open heart surgery which confined itself to the finer points of scalpel technology. The creation of a case register is as simple or as complicated as the clinician wishes it to be; a case register at its purest is simply a list of contacts with patients, organised to a predetermined format, which allows the clinician to gain information from the list for education, research, planning or administration. The work needed to establish a case register, however, should not be underestimated, and the time spent in thinking through reasons for development of a register is a worthwhile investment. An understanding of the history of the development of psychiatric case registers may help those wishing to develop new registers to avoid treading well worn cul-de-sacs, while reviewing some of the work which has resulted from case registers may demonstrate the enormous potential of a well-designed register in facilitating the extension of knowledge about treatment and provision of services.