Understanding stomatal functioning and its role is important since stomata control both photosynthesis, i.e. the production potential, and transpiration, which in turn influences irrigation management. Moreover, it is well known that stressing conditions which induce stomatal closure are needed for flowering in mango. The first striking feature is that mango seems to be well protected against excessive losses of water through transpiration. Stomatal frequency is high but stomata are small, which allows for quick responses to relevant stimuli. Transpiration curves show that a loss of less than 2% of water can lead to complete stomatal closure. Stomatal conductance, gs, is also very sensitive to the ambient concentration of CO2 of the air. This is consistent with the close linear relationship we observed between gs and net photosynthesis, Anet, all year round. High water availability and humidity of the air, plus the presence of an intense sink activity are needed to achieve the highest gs values. Interestingly measurements of chlorophyll fluorescence did not reveal any photoinhibition in high photosynthetically photon flux density and low gs conditions. The practical consequences of these observations are discussed.