Viral infections are characterised by a large expansion of CD8+ effector T cells. Once generated, these T cells must be cleared and homeostasis re-established. In this review we describe two mechanisms, apoptosis and replicative senescence which are thought to play a vital role in this process. Apoptosis clears the unwanted T cells at the end of an immune response whereas replicative senescence prevents unlimited expansion of T cells. For successful memory to be produced T cells must avoid apoptosis and avoid replicative senescence.