The identification and distribution of immunoglobulins and of fibrin by the immunofluorescent antibody staining method was continued. Results to date confirm some amounts of the immunoglobulins and of fibrin in the lesions. We have observed persistent microvascular occlusion in virtually all the hypertrophic scars and keloids, but not in normal or mature scars. The occlusion is due to an increase in the endothelial cells. In extracts of skin, scar, hypertrophic scar or keloid tissue, we have studied specific inhibitory or stimulatory factors to fibroblast proliferation and protein (collagen and proteoglycan) synthesis. So far, we have demonstrated the presence of an inhibitor of fibroblast proliferation. Experiments are continuing to identify this factor and to evaluate the lesions for presence of synthesis stimulators.