Macrophage migration inhibitory factor (MIF) has been shown to play a pathogenic role in kidney disease. This article will review the current understanding of the expression of MIF and its functional role in immune-mediated renal injury in both human and animal models of kidney disease. Upregulation of MIF is found in both human and experimental kidney disease including renal allograft rejection and contributes significantly to macrophage and T-cell accumulation and progressive renal injury. It is now clear that MIF is a stress factor, a pro-inflammatory cytokine, a growth factor and a hormone. MIF acts through many mechanisms to mediate renal injury including the innate and adaptive immune systems, the induction of cytokines, chemokines, adhesion molecules as well as interactions with glucocorticoids and the hypothalamic-pituitary-adrenal axis. MIF exerts its biological activities via signaling through its CD74/CD44 receptor complex to activate the downstream ERK1/2 MAP kinase. The functional importance of MIF in kidney disease is demonstrated by the findings that treatment with a neutralizing anti-MIF antibody is able to prevent or reverse renal injury in crescentic anti-GBM glomerulonephritis. In addition, mice null for MIF are protected against immune-mediated lupus nephritis. MIF plays a critical role in kidney diseases and further studies of the functional role and signaling mechanisms of MIF in human kidney diseases are needed.