A greenhouse experiment was carried out for 2 weeks to test the effect of different levels of NaCl on the growth and nitrogenase activity (ARA) of Azolla filicuiofdes. Results indicate that Azolla friicufofdes can tolerate salinity up to 20 Mm NaCI. Increasing the concentration of NaCl to 40 and 50 mM strongly inhibited the growth of Azofla ( fresh and dry weight). Azolfa was killed within two weeks in presence of 50 mM NaCl. Due to the nitrogen content of Azoffa and nitrogenase activity (ARA), the effect of NaCI was harmful. Increasing salt concentration up to 40 mM NaCl caused Nitrogen content of Azofla fronds to be gradually decreased ARA decreased with increasing NaCl concentration and recorded the lowest nitrogenase activity in presence of 50 mM NaCl.