The rare case of a long common trunk of the two anterior cerebral arteries is described angiographically with reference to three infants. Meningocoeles were present in two patients, while the third exhibited agenesis of the corpus callosum. Porencephalic cysts of different degrees were found in all three cases. The findings included hydrocephalus with concomitant subdural effusion. The highly complex vascular anomaly and the development of multiple venous anomalies represent the general malformation of the brain. An attempt is made to relate this arterial anomaly to embryological development.