This brief review will discuss an exciting new area in exercise science, namely the role of apoptosis or programmed cell death in exercise. Apoptotic cell death differs morphologically and biochemically from necrotic cell death, although both appear to occur after exercise. Accelerated apoptosis has been documented to occur in a variety of disease states, such as AIDS and Alzheimer's disease, as well as in the aging heart. In striking contrast, failure to activate this genetically regulated cell death may result in cancer and certain viral infections. We will discuss factors that may activate apoptosis during and after exercise and the importance of cell turnover after exercise. We will also discuss differences in apoptosis between lymphocyte and skeletal muscle cells. We speculate that exercise-induced apoptosis is a normal regulatory process that serves to remove certain damaged cells without a pronounced inflammatory response, thus ensuring optimal body function.