Roots play a significant role in the salinity tolerance or sensitivity of plants. It was shown that hydraulic conductivities are decreasing with increasing salinity, however, there are evidences that roots of different genotypes could react different under salinity conditions. The plasticity of the root hydraulic system to salt stress is far less understood than salt-exclusion or osmo-regulation mechanisms, especially in woody species. Differences in salt sensitivity of fruit trees were often attributed to their salt exclusion capacities. A suggested alternative mechanism is a change in xylem anatomy. Root hydraulic conductivities and anatomical adjustments of three drip irrigated varieties of olive (Olea europaea L.), ‘Barnea', ‘Arbequina' and ‘Proline' considered as high and moderate tolerant and sensitive to salinity respectively were examined. Three levels of salinity (1.2, 4.2 and 7.2 dS m^-1) were applied on mature ‘Barnea' trees, and two salinity levels (1.2, 4.2 dS m^-1) on ‘Arbequina' and ‘Proline'. Fine and coarse roots of the three Olive varieties showed an overall increase in specific conductivity as salinity levels increased. Anatomical analysis showed that this is not due to larger average of xylem vessel diameters but rather due to higher densities of conductive area in the stele. There is evidence for an amplified functional differentiation of fine roots especially at high salinity (7.2 dS m^-1). 80% of the sampled ‘Barnea' roots had lower specific conductivities compared to the 1.2 and 4.2 dS m^-1, and the rest showed much higher values. This might be due to a forced specialisation in ‘high conductivity' roots, which might be favourable to water uptake in soils with heterogeneous salinity. The anatomical study confirmed these experimental results by identifying very large xylem vessels in these roots. In respect to embolism rates, salinity showed no consistent influence, which could be explained by more or less unaltered average vessel diameter.