Annual species of 'Medicago' genus play an important role in improving fodder production in Algeria. Medicago truncatula Gaertner is the plant model of leguminous. This kind of plant is very important for natural soil fertilisation and also good quality nutrition for animals and human for their richness in protein. However, abiotic stresses like salinity are the major cause of land degradation and crop productivity limitation around the world and affects physiology and metabolism in legumes. In this study, we analyzed the behaviour of pollen tube growth in two contrasting Medicago truncatula ecotypes under salt stress (Tru 42, tolerant and Tru 242, sensitive one) with different concentration of NaCl. (68, 102 and 137 mM) because pollen tube growth mechanisms can be affected by environmental stresses such water and salt stress. The salinity stress can prevents male gametophyte to accomplish reproduction and it’s Important to understand the male gametophyte physiological responses to accomplish reproduction. The analysis showed that the tolerant ecotype has good pollen tube elongation compared to the sensitive one and it’s interesting to introduce the tolerant genotype in selection program for leguminous breeding. Actually, no enough information was available on pollen tolerance mechanism to salt stress in Medicago truncatula or other Medicago species.