This study deals with the applicability of Araldite F as injection medium for quantitative morphology of the cerebral vascularization. The physical properties of the plastic that are essential for obtaining optimal results have been determined and tested by injection into the cerebral vessels of ten dog brains and five human brains. The dynamic viscosity (at 20 degrees C) of the plastic is 1.5 times that of blood. The polymerization time (+/- 45 min) is long enough to fill the whole vascular tree in a large organ such as the human brain. The plastic shows minimal volume shrinkage (3.90% +/- 0.05%), and the final cast is suitable for scanning electron microscopy (SEM) investigation after corrosion and histological morphometrical examination after embedding in 2-hydroxyethyl-methacrylate (GMA). Special attention has been paid to the conditions under which injection of Araldite F into the cerebral arteries must take place to obtain the most accurate quantitative data on cerebral vascularization and vascular area distribution. Simultaneous injection of the major cerebral arteries of fresh autopsy material, after having removed blood clots by perfusing Kabikinase, is recommended.