New olive (Olea europea L.) orchards are being implanted in many semi arid areas, where saline water is the main source of water available crop irrigation. Olive is moderately tolerant to salinity. Still saline effects on olive root development has not yet described adequately. Plant roots are adapted to absorb water and nutrients from the soil to provide necessary ingredients for optimal growth and development of the plant. The function of roots is profoundly influenced by soil nutrient composition, the presence of toxins and by biotic and abiotic environmental stresses. In the present study, root development of olive (cv Barnea) were compared under saline drip irrigation (4.2 dS m^-1) and control (1.2 dS m^-1), A minirhizotron (MR) system consisting on a miniature video camera was used for monitoring root development; Clear acrylate tubes with 52 mm inner and 60 mm outer diameter, were inserted to the soil at three distances (50, 100 and 150 cm) from the trunk down to the depth of  2 m. The tubes were installed on May 5, 2005 and the measurements started one month later. The observations were taken once a month for 18 months. Soil SAR and Salinity was measured with depth.  Total root number in the saline treatment was considerably smaller in comparison with the control. Total root length was larger in olive trees irrigated with freshwater. Root surface area was smaller in the saline water treatment compared to the freshwater treatment. Unlike root number and root length, root surface area continued to increase throughout the observed period in both the treatments. Root distribution with depth and distance from the trunk varied between the two water quality treatments. This study suggests that salinity plays an important role in root distribution and development in olive trees.