Retrospective analysis in co-operative study of hydrocephalus at institutions of members of the Research Committee on Intractable Hydrocephalus sponsored by the Ministry of Health and Welfare of Japan was performed to determine the functional prognosis. For clinico-epidemiological study we classified non-tumoral hydrocephalus into eight types based on its etiology and the time of onset. Analysis of the 1,450 cases of hydrocephalus stored in the database obtained from the study was performed in order to find intractable factors in terms of factors related to patients and management. Analysis of the cases stored in the database revealed that the following types and conditions were found to be intractable factors: 1. Early fetal hydrocephalus. 2. Overt neonatal hydrocephalus. 3. Hydrocephalus associated with such severe brain malformations as hydranencephaly, holoprosencephaly and lissencephaly. 4. Hydrocephalus associated with severe brain damage. 5. Hydrocephalus associated with epilepsy. 6. Hydrocephalus shunted late after detection. 7. Hydrocephalus complicated by a shunting operation. It is impossible to determine prior to treatment whether or not a shunting operation is indicated for the patient with intractable factors, however, they may be a useful pre-operative indicator of prognosis. For the management of hydrocephalus, secondary intractable hydrocephalus may be preventable if we treat it appropriately before it becomes intractable.