Interleukin 10 (IL-10), a cytokine with inhibitory activity on inflammation and cell -mediated immune responses (CMIR), holds enormous potential for the treatment of inflammatory and autoimmune disorders. In addition, IL-10 has also been implicated in the immunopathogenesis of a number of infectious diseases through the use of IL-10 knock-out or IL-10 transgenic mouse models. In this review, we delineate infectious and inflammatory conditions in which IL-10 has shown potential for therapeutic manipulation. Specifically, we review the role of IL-10 in human endotoxemia/sepsis and in HIV infection, conditions for which preliminary phase I trials have recently been undertaken. It is suggested that the therapeutic potential of IL-10 to selectively ameliorate human infectious and inflammatory processes can be realized through a careful selection of the clinical conditions in which patients are undergoing concomitant treatment with anti-microbial regimens.