Recent progress in trials of regeneration and gene therapy in endocrine organs, especially in adrenal glands has been reviewed. Gene therapies using adenovirus have been most frequently tested in vivo and in vitro, aiming at improvement of steroidogenesis and suppression of adrenal tumor growth. Although the effects were temporal, promising results have been obtained. Interestingly, adrenocortical tissue was shown to be formed by transplantation of adrenocortical cells and to replace the adrenal functions of adrenalectomized animals. Engineered ES cells stably expressing Ad4BP/SF-1 were shown to be directed toward steroidogenic lineage, suggesting a future possibility of regeneration of adrenal cells.