While Considerable attention has been applied to the contrast medium evaluation of the cerebrospinal fluid pathways in the assessment of congenital abnormalities of infancy and childhood, angiography has to a large extent been neglected. Recently, however, more attention has been given to the appearances of the venous and sinus phases of the angiogram in elucidating and diagnosing some of the abnormalities (9). This paper constitutes a study of the latter phases of the angiogram in certain selected congenital abnormalities and an attempt at formulating a unifying concept to account for the venous appearances. Material Cases of occlusions of the foramina of Magendie and Luschka (Dandy-Walker syndrome), infratentorial arachnoid cysts, supratentorial cysts, aqueduct stenosis, and communicating hydrocephalus were selected for this study. An analysis of the cases and the procedures carried out is described in TABLE I. In the angiograms particular attention was paid to the configuration of the straight sinus, confluence of sinuses, and transverse sinuses. To enable the different appearances to be analyzed certain measurements were obtained of the skull circumferences with special reference to the nasion-inion distance, and the inion-posterior lip of foramen magnum distance. Furthermore, the angle between the slope of the straight sinus and a line joining the nasion with the tuberculum sella was assessed in all cases (Fig. 1). It was thought that this angle was a fairly reliable guide to the configuration of the medial slope of the tentorium. A control series of 35 normal angiograms in infancy and childhood was similarly analyzed. A second control series of 13 normal pneumoencephalograms in which sufficient air was subtentorially present to outline the undersurface of the tentorium was also selected. This enabled the same tentorial angle to be determined. From these two series it became apparent that the slope of the straight sinus conformed well with a line joining the inion and the anterior fontanel. A third control series was then obtained of 12 normal skulls in which the tentorial angle was assessed by utilization of the angle between the nasion-tubercu-lum sella line and the inion-anterior fontanel line. Finally, a series of 10 abnormal cases in which air studies but no angiograms were available was similarly analyzed. Figures 2 and 3 demonstrate the ratios of the nasion-inion to inion-foramen magnum distances and to the tentorial angles in the normal and abnormal cases. Figure 4 is from a case of Dandy-Walker syndrome with a high position of the torcular and poorly developed transverse sinuses. Figures 5 and 6 are examples of high torcu-lars with elevated transverse and straight sinuses in cases of posterior fossa arachnoid cysts. These appearances are therefore not specific for the Dandy-Walker syndrome.