Following subarachnoid hemorrhage, a considerable number of cases develop disturbances of cerebrospinal fluid dynamics. The author studied the criteria of indication of cerebrospinal fluid shunting operation in clinical cases of subarachnoid hemorrhage following the rupture of intracranial aneurysm. The author conducted (169)Yb-DTPA cisternography in 34 patients with ruptured intracranial aneurysm, and 0.3-0.5mCi of (169)Yb-DTPA was injected by lumbar puncture. Brain scintigrams were taken in various projections at 1, 2, 6, 24 and 48 hours, and at the same time blood was withdrawn at regular intervals up to the 6th hour. Then, the transport of (169)Yb-DTPA from the subarachnoid space to the blood was evaluated. Twenty-six cases out of 34 developed disturbance in cerebrospinal fluid dynamics with reflux of (169)Yb-DTPA to the ventricles. Studying further these cases the blood (169)Yb-DTPA concentration curve within the period of 1-2 hours after (169)Yb-DTPA injection by lumbar puncture, is likely to reflect the (169)Yb-DTPA transport from the intrathecal subarachnoid space to the blood, but cases in which (169)Yb-DTPA absorption from the intrathecal space was poor, had the dilatation of the cerebral ventricles, while those with good absorption except one case had no dilatation. Cases with moderate to marked degree of dilatation of the ventricles, were accompanied with mental, gait disturbance and incontinence, and they were taken the cerebrospinal fluid shunting operation. Cases in which complete lack of cerebral convexity filling of (169)Yb-DTPA was seen in 24-hour scintigram, were clinically benefited, while cases in which both ventricular dilatation and stasis were seen and moreover convexity filling was observed, were not benefited by shunting operation.From these findings, the considerable dilatation of the ventricles, the ventricular stasis and the complete lack of convexity filling of (169)Yb-DTPA at 24 hours in cisternography, and the malabsorption of cerebrospinal fluid in the intracranial as well as intrathecal space are reliable criteria in determining the indication of the cerebrospinal fluid shunting operation for the patients with specific clinical symptoms.