The nasal tip blood supply was studied through anatomic dissections and microangiography in 31 fresh cadaver specimens. The lateral nasal artery was present in all specimens, bilaterally in 30 (97 percent) and unilaterally in one (3 percent) and was located in the subdermal plexus 2 to 3 mm superior to the alar groove. The columellar branch of the superior labial artery was visualized bilaterally in 3 specimens (9 percent) and unilaterally in 21 (68 percent), and was absent in 7 (23 percent). Transcolumellar (external rhinoplasty) incisions were performed in 11 of these cadavers prior to dye injection. A consistent crossover flow (100 percent) was seen from the lateral nasal artery arcades to the distal aspect of the transected columellar branches. We conclude that nasal tip blood supply is derived primarily from the lateral nasal arteries, with a variable contribution from the columellar arteries. Collateral flow to the nasal tip may be provided by branches of the ophthalmic artery. The external rhinoplasty transcolumellar incision does not compromise nasal tip blood supply unless extensive tip defatting or extended alar base resections (above the alar groove) are performed.