Experience from 64 operations of free transplantation of autogenous and allogenous skin grafts in alopecia by the Orentreich method is reported. Studies were made of the morphologic condition of autoallotransplants of skin, changes in the activity of enzymes in the peripheral blood and antithrombocytic antibodies and complement of the serum. It was established that the Orentreich operation leads to a durable healing of autogenous skin grafts. Transplantation of allogenous transplants enhances the stimulation of the growth of hair in the area of skin around the transplant. It was discovered that some connection exists between the life span of allogenous skin and the degree of compatibility with respect to the ABO antigenic system, Rh factor and leukocytic antigens of the HL A system.