Fifteen New Zealand rabbits were used in this study. Buffered saline solution was given through the common carotid artery to remove the blood from the cranial veins. The jugular vein was ligated prior to giving blue latex to 10 rabbits and blue Batson's No. 17 to 5 rabbits through the maxillary vein. Rabbits were left for 24 hours in order to let the latex harden and then they were transferred to 10% formaldehyde solution and dissected. Rabbits that were injected with Batson's No17 were kept in 33% KOH solution for 48 hours and corrosion casts were prepared. The diameters of the veins were measured with a digital dial caliper.