There is a large amount of current research investigating the pathophysiologic aspects of pulmonary hypertension. Results of this research indicate the potential role of the macrophage as one possible mediator of pulmonary hypertension. The macrophage has been shown to produce numerous soluble mediators, including various growth factors, some of which may be involved in the cellular proliferation of the arterial wall. Most of the knowledge regarding oxygen microenvironments, macrophages, and growth factor production comes from research on the healing wound. A considerable amount of what has been learned about the role of the macrophage in cutaneous wound healing may have direct applicability to macrophage function in acute lung injury and repair, and pulmonary hypertension. Macrophages play a pivotal role in cutaneous wound repair. They participate in immunologic and nonspecific host defense responses and produce numerous growth factors that regulate mesenchymal cell proliferation, migration, and synthesis of extracellular matrix proteins. These same responses are probably at work during the progression of pulmonary hypertension.