Artificial skin is a recent development in the clinical care of the severely burned patient. Its manufacture entails the covalent bonding of collagen and polysaccharide, followed by the coating of one surface with a thin layer of silicone rubber. Artificial skin was grafted onto rats and examined for neovascularization at 7 days. Vascular patency was shown by perfused yellow latex casts. Five percent of the patent vessels grew into the graft soaked in physiological buffered saline (PBS). When the graft was soaked in heparin, 1 mg/ml buffered saline solution, before grafting, 54% of the patent vessels in the grafted area had grown into the matrix. These experiments show that the local application of heparin promotes early ingrowth of blood vessels into the healing site. The vascularity of artificial skin can be modified by heparin, which promotes angiogenesis, and leads to earlier deposits of greater amounts of new connective tissue.