Abstract: The main objective of this study was to investigate the impact of short-term light intensity changes in relation to crop loading on the net photosynthesis (A) and stomatal conductance (gs) of grapevine (Vitis vinifera L.) cv. Pinot noir. Shading caused a rapid increase in the net photosynthesis (A) and stomatal conductance (gs) of the illuminated part of the canopy. Fruiting grapevines had a higher A and gs (4.7 μmol CO2 m–2 s–1 and 0.08 mol H2O m–2 s–1, respectively), than non-fruiting vines (2.9 μmol CO2 m–2 s–1 and 0.05 mol H2O m–2 s–1, respectively). Intercellular CO2 concentration (Ci) was unaffected by shading or crop loading, It is concluded that crop load has significant role in the rapid changes in A and gs in the illuminated part of the canopy.