This study was designed to study the microvascular anatomy of the basilar artery between the superior cerebellar artery and the vertebrobasilar junction (i.e. the lower basilar artery). Twenty unfixed brains were injected with silicone rubber solution and studied with a Zeiss OPMI microscope. The length of this segment of the basilar artery was 28.1 + 1.35 mm and its course was straight in 9 (45%) brains, curved in 7 (35%) and tortuous in 4 (20%). The total number of perforators found in 20 brains was 340 with an average of 17 per brain. Of these, 118 (34.7%) were median and 222 (65.2%) were lateral. Median branches had a mean length of 5.8 + 1.25 mm, whereas left and right lateral branches had a mean length of 16 + 1.25 mm and 16 + 1.58 mm respectively.