The Aim of this study was to determine the effect of salinity on development of the root system of Tamarix aphylla, a typical tree of deserts from North Africa to Central Asia. Cuttings were planted in April 2004 in an experimental plot in the Northern Negev of Israel. Two salinity treatments were given through a trickle irrigation system: Control (1.4 dS/m) –irrigated with tap water supplemented by fertilizers, and Saline (13.0 dS/m) - irrigated with the same fertilizer solution to which 100 mM NaCl salt was added. Irrigation rate was 10m3 hectare/week. Measurements of root growth were done using a minirhizotron system. Transparent tubes were inserted vertically into the ground to the depth of 170 cm. Root growth was monitored in seven days intervals for the first three months and afterwards in intervals of 14 to 21 days. After 7 months the average tree height was 165 cm. Within a few weeks after planting the first roots have reached the depth of 150 cm. Roots were shorter in the saline treatments as compared to those in the control. The largest difference in root length was found at the depth of 100 cm. Down to the depth of 72 cm, root length was larger in the saline treatment than in the control. The number of roots in the saline treatment increase gradually down to 65 cm, followed by a decrease down to the depth of 80 cm. Results show that Tamarix aphylla has an extremely fast root growth and reaches deep soil layers in a very short time. This could be an important characteristic that contributes to its survival on desert sand dunes. The plants exhibited rapid root and shoot growth even under saline conditions. Therefore they can be used for reclamation and biomass production in marginal habitats in desert borders.