Visfatin is a highly conserved protein expressed by visceral fat tissues that previously identified as pre B cell colony-enchancing factor (PBEF). Visfatin is a 52 ku cytokine and has been shown to exert multiple distinct biological activities. By interacting with insulin receptors, visfatin exhibits insulin mimicking or antagonizing effects under different circumstances. In addition, it possesses an nicotinamide phosphoribosyl transferase (Nampt) activity inside the cells, which functions at the rate-limiting step along the pathway of nicotinamide adenine dinucleotide (NAD) biosyntheses. And finally, as an extracellular cytokine, visfatin is able to induce the expression of inflammatory cytokines, such as TNFα, IL-1β and IL-6. Visfatin has drawn increasing attentions to researchers for its close association with a variety of human metabolic and acute/chronic inflammatory diseases or disorders, including diabetes, obesity, acute lung injury, rheumatoid arthritis, sepsis, myocardial infarction and inflammatory bowel disease. Recently, the SNP (single nucleotide polymorphism) analyses of visfatin and its promoter regions have provided more in-depth understandings of its roles in disease pathogenesis. A discussion in the current knowledge of the structure and diversified functions of visfatin, as well as its connections with a variety of common diseases was given.