Oxygen-free radical production and reperfusion injury are complex mechanisms. New and improved methods for maximizing the benefits of reperfusion while minimizing reperfusion injury are on the horizon in the 1990s. Critical care nurses play a crucial role in the assessment, planning, and intervention of patients experiencing the deleterious effects of free radicals and reperfusion injury. Thus, a sound knowledge base in the pathophysiology of reperfusion injury, the detrimental effects of free radicals, and the potential benefits of free-radical scavengers is essential.