Macrophage migration inhibitory factor (MIF or MMIF), also known as glycosylation-inhibiting factor (GIF), is a protein that in humans is encoded by the MIF gene. MIF is an important regulator of innate immunity.

MIF is an inflammatory mediator associated with rheumatoid arthritis (RA) severity. MIF protein levels are increased in the plasma of people with schizophrenia, including people in the early stages of the illness, but the clinical significance of this has not been determined. It has also been shown to induce changes in the heart during sepsis. Evidence suggests that there is a correlation between MIF production and metastatic potential in colorectal cancer. In addition, it was reported that there is an increased MIF production in Alzheimer’s disease and mild cognitive impairment.