Endothelial Cell Medium (ECM), when used with Endothelial Cell Growth Supplement (ECGS, Cat #1052) and 25 ml of fetal bovine serum (FBS) is a complete medium designed for optimal growth of normal endothelial cells in vitro. It is a sterile, liquid medium which contains essential and non-essential amino acids, vitamins, organic and inorganic compounds, hormones, growth factors, trace minerals and a low concentration of fetal bovine serum (5%). The medium is HEPES and bicarbonate buffered and has a pH of 7.4 when equilibrated in an incubator with an atmosphere of 5% CO2/133% air. The medium is formulated (quantitatively and qualitatively) to provide an optimally balanced nutritional environment that selectively supports the growth of normal endothelial cells in vitro.