Vascular Endothelial Growth Factor (VEGF) is a potent angiogenic factor under both physiological and pathological conditions including tumour angiogenesis. Expression of VEGF in mammary gland was studied. VEGF was detected in epithelial lining of ducts, acini and endothelium of blood vessels as well as around fat cells. It was detected in nulliparous rat mammary gland. VEGF was increased in early pregnancy with marked increase in late pregnancy. Maximal VEGF expression was detected during lactation. VEGF was also detected in milk. During involution VEGF expression decreased progressively with marked decrease in late involution. Human samples showed more VEGF in females in child bearing period than post menopausal female mammary gland. The changes in VEGF expression could be related to hormones