Tamarix aphylla trees occupy a distinct zone along the sand dune in Oyoun Mousa region. Genetical and physiological studies on the oldest tree T. aphylla and the T. nilotica species in the same region were carried out. Electrophoretic analysis of total soluble protein (SDS-PAGE) and some isoenzymes; such as acid phosphatase (ACPH), esterase (EST),   peroxidase (POD) and 6- phosphogluconate dehydrogenase (6PGD) revealed that T. aphylla exhibited higher number of polypeptides and isoformes. This finding might suggest that T. aphylla plants are more tolerant to salt stress than T. nilotica. This could be accomplished by increasing the capacity of antioxidative system, synthesis of new protein and isoenzymes, which could in turn contribute to some defense mechanisms of tolerant plant. Random Amplified Polymorphic (RAPD) DNA markers were used to measure genetic diversity of the two species. A total of 50 amplified bands were scored with the used of 8 RAPD primers, with a mean of 6.2 amplified bands per primer, and 66% (33 bands) of polymorphic bands were found. The use of DNA markers, OPA-7, OPA-10, OPA-15 and OPB-4 distinguished  bands with size ranging from 1655 to 2500 bp in T. aphylla only and absent in T. nilotica.