Localised irradiation in large enough dosage prejudices successful autologous skin transplantation in the rabbit. It appears that the deleterious effects of irradiation in this respect are first manifested in the graft itself; at higher doses, damage to the recipient site prevents takes. At the qualities of irradiation used in these experiments (HVL 0·31 mm of Al and 2·2 mm of Al), 2,200 r to the donor skin prevented successful grafting whereas this dose to the recipient site showed no significant diminution in percentage of graft takes as compared to control levels. Administration of cysteine intravenously just before irradiation afforded partial protection to the donor skin.