A total of 14 grapevine accessions (8 Vitis species and 6 cultivars) were examined in order to elucidate the relationships between photosynthetic activity and light intensity, Photosynthetic rate (Po, mgCO_2/dm^2/hr) of grapevine leaves increased in accordance with the level of light intensity. Although great differences were observed within genus Vitis, light saturation point (S.P) and light compensation point (C.P) generally ranged from 20 to 40klx and from 0.2 to 2.0 klx, respectively. In general, dark respiration (D.R, mgCO_2/dm^2/hr) and C. P were higher in high temperature than in low one. Until 20 klx of light intensity, transpiration (Tr, gH_2O/dm^2/hr) and stomatal conductance (gl, cm/sec) linearly increased in consistent with the increase of intensity, and thereafter increased progressively. Water use efficiency (Po/Tr ratio, mgCO_2/gH_2O) increased linearly until 20 klx of light intensity. The Po/tr ratio was low in high temperature. Intercellular CO_2 concentration (Ci, ppm) decreased with the increase of light intensity. Compared with grapevine accessions which are grown in low latitudes, those in high latitudes showed the low Po under high temperature together with the low S. P, C. P, Tr and gl. In the cultivars eventhough having the same parentage, large varietal differences in the Po, Tr, gl, and Po/Tr ratio were found.