16 p.To validate the use of hemispherical photography as a method of determining leaf area index (LAI), on apple and cherry trees, an essay was carried out on 2 orchards in the VII Region, Chile, during 2002-2004 seasons. For apples, cultivars Royal Gala, Red Chief, Braeburn and Fuji, planted in 1990-1992 on seedling rootstock, (740 to 1250 plants/ha) were used. Cherry cultivars were: Lapins, Summit, Van and Bing, planted in 1997 on Mahaleb rootstock, (800 to 1000 plants/ha). For both species, 5 trees per cultivar were photographed, taking 4 pictures per tree during 2002/2003 season and 15 – 24 pictures per tree during 2003/2004 season, depending on planting density. A digital camera was used, which was adapted with a hemispheric lens (fisheye). In order to validate the ability of the software to estimate the actual values, the same trees were defoliated by hand, and real LAI was calculated. Correlation analyses were made between real and estimated LAI. The degree of accuracy reached by hemispherical photography was very low for apples, during the first season (r=0.27). However, during 2003/2004 season an important increase in the correlation was obtained (r=0.52), being the amount of pictures taken per tree highly determinant on this fact. For cherry trees, the correlation coefficients varied between 0.73 and 0.84, and the amount of pictures per tree seemed to be less determining in the estimation of the LAI.