The recent development of blood purification methods is remarkable. Now the physician can choose a different method and apparatus for blood purification according to the condition of each patient. Unlike the days when a uniform therapeutic method was used on all patients, the method and apparatus used on each patient may differ, and therefore if an inappropriate method or apparatus is used, it may result in a serious medical error. Patients on dialysis are in a pathologic state brought about by the causative disease and that brought about by renal failure which can not be cured by blood purification therapy. Therefore, it is necessary to accumulate a large amount of information on the patient's condition, including tests, and to use them effectively to provide optimum management of the patient. The author developed a system to collect and analyse large amounts of such information by using a microcomputer to help improve the practise of dialysis, and enable more appropriate patient management. The input of this system are basic data on the patient, information relating to dialysis treatment, symptoms of the patient, results of tests, treatment applied etc.; its output are medical bills, drug requisition sheet, dialysis record etc. Simultaneously, the various pieces of information stored by this system can be retrieved as required. The planned objective of this system has been achieved in the past 8 months.