Wythenshawe Hospital is a large general district hospital with more than 1000 beds, situated approximately 9 miles south of Manchester. The Cardio-Thoracic department, housed in the new section of the hospital which was completed in 1973, is the major centre for cardiothoracic surgery in the greater Manchester area. It also receives any major accident cases which require treatment within the Intensive Therapy Unit. This paper describes a Patient Data Display System and the methods used to introduce the concept of such a system, to doctors, nurses, laboratory and paramedical staff, and the manner in which these staff were trained in the use of computer terminals. Principles underlying the need for and requirements of such a system are also discussed. Six months after hardware commissioning the system was fully operational throughout the whole department.