Publisher Summary Although initially identified as a cytokine that promotes pre-B cell growth, it is now clear that IL-7 mediates effects on a wide range of cell types. Data generated during the past several years have demonstrated the exciting immunomodulatory potentials of IL-7 in T cell mediated immune responses. However, the potential use of IL-7 to promote B and T cell lymphopoiesis in clinical settings has yet to be meaningfully evaluated. Similarly, the role for IL-7 in augmenting immune responses in clinical settings to antigens expressed on tumor cells, to parasitic infections, and to viral antigens also awaits investigation. It is hoped that the results of studies in these areas will soon be undertaken to determine whether the promise shown by this cytokine in pre-clinical studies will be borne out. Certainly, the addition of a cytokine with the substantial beneficial immunomodulatory activities attributed to IL-7 in both in vitro and in vivo studies in murine systems, and in vitro studies using human lymphoid cells, would be a welcome addition in the immunotherapeutic treatment of cancer and HIV.