Nicotinamide phosphoribosyl transferase (NAMPT) is the key enzyme for the synthesis of nicotinamide adenine dinucleotide (NAD), and also serves as a cytokine in mammalian cells. NAMPT is known to participate in biological responses such as glucose metabolism, inflammatory response and stress. Recent studies have revealed that NAMPT is closely associated with aging and age-related diseases such as diabetes, obesity, cancers, neuronal degeneration and cardiovascular diseases. Research on NAMPT may provide insight on prevention and treatment of related diseases.