Angiogenesis is the process by which new blood vessels are formed from existing vessels. Mammalian populations harbor genetic variations that alter angiogenesis. Some of these changes result in Mendelian traits of variable penetrance, with telangiectasia being a common symptom. Other more subtle variations exist, with promoter variations in the VEGF gene being of particular interest. Genetic diversity in angiogenesis-regulating genes has been linked to increased susceptibility to multiple angiogenesis-dependent diseases in humans. These diseases include cancer, arthritis, atherosclerosis, and cardiovascular disease, endometriosis, diabetic retinopathy, retinopathy of prematurity, psoriasis, and sarcoidosis. Also, multiple disturbances in pregnancy including miscarriage, spontaneous preterm delivery, and severe pre-eclampsia have been linked to alterations in angiogenesis-regulating genes. Present efforts to dissect the complexity of the genetic diversity that regulates angiogenesis have used laboratory animals due to the availability of genome sequence for many species and the ability to perform high volume controlled breeding. Ongoing mapping studies have identified multiple loci that control angiogenic responsiveness in several mouse models. Genetic alterations responsible for discrete angiogenic alterations will then be studied in appropriate mouse disease models.