Research into vascular prostheses lined with endothelial cells is being carried out for the purpose os using these prostheses in occlusive arterial diseases. As it is very difficult to use endothelial cells (EC) from the patient, we suggest that EC from the umbilical veins of newborns be conserved for use in the future. This paper details our present research on some experiments with EC from umbilical veins. Cells are cryopreserved following three ways: in situ in the umbilical cord; isolated and meintained in suspension; and, preservated in their own culture flask after in vitro culture. The usual culture media for cell cryopreservation techniques were used. After a preservation period in liquid nirtogen, cells were thawed, and a study of cell viability in culture was made.