In the Netherlands, systematic central registration of psychiatrie in-patients has been carried out from the beginning of this century. This compulsory registration was based upon the Insanity Act of 1884. It has been replaced in 1967, when psychiatrie hospitals and the inspectorate for mental health agreed upon a fully computerized, national case register, in which the hospitals voluntarily participated. To-day, this case register covers the in-patients activities of 85,3 % of the psychiatrie hospitals, 100 % of psychiatrie units in university hospitals, 66,2 % of psychogeriatrie longstay annexes and 69,2 % of hospitals for the mentally retarded. After a renovation of the system in 1978, there has been some resistance to co-operate for fear of jeopardizing the privacy of psychiatrie patients. Therefore, it is suggested that patient-tied data should be only collected on a district level, where Regional Institutes for Mental Health Care will be founded. The strictly necessary information should be forwarded by these institutes to a national level but should not contain any patient-tied data. The district and national collecting of data should be regulated and compelled by law.