Abstract: Defibrinated and lyophilized placental cells are prepared by taking the foetomaternal placenta of a ewe killed at the end of the fourth month of gestation, breaking the placenta into fragments, immediately submerging the fragments in Ringer's solution to wash away traces of blood, finely dividing the fragments, placing them in 5% aqueous trypsinated solution, permitting tryptic digestion with stirring, separating the placental cells by filtering, washing the cells in refrigerated Hanks solution, centrifuging in a low temperature centrifuge, suspending the base obtained in the centrifuging step in a minimum of survival liquid and lyophilizing the suspension until constant weight is obtained. The cells obtained are used in the external treatment of ulcers and first and second degree burns.