An immortalized human endothelial cell line was obtained by transfecting umbilical vein endothelial cells in primary culture with plasmid pMK16 containing SV40 replicated origin defective gene. The essential functional properties demonstrated in these immortalized human endothelial cells also retaining the classical phenotypical characteristics of endothelial cells in primary culture are: (1) endothelin-1 secretion; (2) capacity to convert big endothelin-1 into endothelin-1; (3) the capacity to secrete IL1 beta and IL6 interleukins both spontaneously and after lipopolysaccharide (LPS) stimulation; (4) arginine transfer from the extracellular to the intracellular medium. Such stable cell line could facilitate studies of regulation of endothelin-1 production; (5) No-synthase activity; (6) binding and metabolisation of acetylated low-density lipoproteins.