Non-human primates (NHP) have become an indispensable model in studying the common and dangerous human chronic infections, including HIV/SIV, Hepatitis C virus, and tuberculosis. More recently, we and others have used aged NHP to model human immune aging. Chronic infections and aging are both characterized by a significant depletion of defined lymphocyte subsets and the compensatory attempts to regenerate the immune system. As the efficacious antiviral drugs and novel methods to improve and boost the immune system emerge, therapeutic immune regeneration has become a realistic goal in both the physiologic and pathologic settings. This article will summarize our current knowledge on this topic and will discuss future research directions as well as the potential and power of translational studies in non-human primate models of infection, aging and bone marrow transplantation.