In a syngeneic rat model, the present study investigated the cryobiology of fetal adrenal glands and compared the endocrinological function of cryopreserved versus fresh fetal adrenal transplants in the adrenalectomized hosts. Ultrastructural studies showed no significant tissue damage by the cryopreserving technique: cellular membranes were intact, the mitochondria showed discrete swelling and vacuoles were found in the endoplasmatic reticulum. Following transplantation, maturation and bilateral adrenalectomy in the host, assessment of endocrinological parameters demonstrated that survival was prolonged and Addison crisis could be prevented in both transplant groups with no significant difference between fresh versus cryopreserved grafts. To our knowledge this study presents the first morphological and endocrinological data about the successful transplantation of cryopreserved fetal adrenal glands in rats. In conclusion, cryopreservation is tolerated well by the tissue and long-term banking may therefore contribute to the feasibility and benefit of fetal adrenal transplantation. However, further investigations will be necessary to evaluate fetal adrenal transplantation in an allogeneic and xenogeneic setting.