Interleukin-16 (IL-16) was the first described T lymphocyte chemoattractant. It has since been shown that IL-16 also functions as a primer of T cell proliferation, a modulator of inflammatory and immune responses, a stimulus of B cell differentiation and an inhibitor of Human immunodeficiency virus (HIV) replication. Its precursor, Prointerleukin-16 (pro-IL-16), is expressed in both the nucleus and cytoplasm of T cells. Cytoplasmic pro-IL-16 serves as the precursor for mature IL-16 while nuclear pro-IL-16 is associated with G0/G1 cell cycle arrest. Herein, we review the ability of IL-16 to act as both primer and modulator of T lymphocyte growth. The impact of IL-16 on T cell apoptosis is also discussed. Finally, we describe the role of pro-IL-16 as a T lymphocyte cell cycle growth suppressor.