Nitric oxide is a highly reactive molecule with dichotomous regulatory roles in numerous physiological and pathological events. It has been recognized as an intra-and inter-cellular signaling molecule in animals, plants and microorganisms. Recent research data indicate that fungi are capable of synthesizing nitric oxide. Appropriate amounts of nitric oxide play important biological roles in fungal cells. However, excessive amounts of nitric oxide will damage cells and evoke apoptosis. Nitric oxide regulates the synthesis of cGMP, an important intracellular secondary messenger molecule, involved in the control of a variety of signal transduction pathways in fungal cells. Nitric oxide regulates the cellular development, morphogenesis, sporulation, spore germination, reproduction and apoptosis in fungi. Nitric oxide affects the physiological function of fungi throughout the life cycle. Although the mechanism of nitric oxide in plants and animals has been widely studied, there are limited reports about nitric oxide in fungi; and further investigation is needed to illustrate the nitric oxide synthesis, degradation pathways and the mechanism of signal transduction in the fungal system.