This study investigated the effects of early excision of eschar and grafting with cyclosporin immunosuppression on immunological changes following burn injury. The immunological status of the rat was studied using two in vivo measures following a (30 per cent TBSA) full skin thickness burn injury. Cyclosporin was found to be a powerful immunosuppressive agent in skin transplantation, and its risks, efficacy and possible subjects after thermal injury have been investigated. This study demonstrated that a large burn was profoundly immunosuppressive, and early excision and grafting was able to restore cell-mediated immunity significantly as reflected by two in vivo assays. The short course of the immunosuppressive treatment to delay skin allograft rejection did not cause a severe additional effect on cell-mediated immunity after thermal injury. Allograft survival appeared to be related to immunosuppression caused mainly by cyclosporin treatment and also by the immunosuppressive effect of the burn.