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Increased soil salinity, and therefore accumulation of ions, is one of the major abiotic stresses of cultivated plants that negatively affect their growth and yield. Among Medicago species, only <i>Medicago truncatula</i>, which is a model plant, has been extensively studied, while research regarding salinity responses of two important forage legumes of <i>Medicago sativa</i> (<i>M. sativa)</i> and <i>Medicago arborea</i> (<i>M. arborea</i>) has been limited. In the present work, differences between <i>M. arborea</i>, <i>M. sativa</i> and their hybrid Alborea were studied regarding growth parameters and metabolomic responses. The entries were subjected to three different treatments: (1) no NaCl application (control plants), (2) continuous application of 100 mM NaCl (acute stress) and (3) gradual application of NaCl at concentrations of 50-75-150 mM by increasing NaCl concentration every 10 days. According to the results, <i>M. arborea</i> maintained steady growth in all three treatments and appeared to be more resistant to salinity. Furthermore, results clearly demonstrated that <i>M. arborea</i> presented a different metabolic profile from that of <i>M. sativa</i> and their hybrid. In general, it was found that under acute and gradual stress, <i>M. sativa</i> overexpressed saponins in the shoots while <i>M. arborea</i> overexpressed saponins in the roots, which is the part of the plant where most of the saponins are produced and overexpressed. Alborea did not perform well, as more metabolites were downregulated than upregulated when subjected to salinity stress. Finally, saponins and hydroxycinnamic acids were key players of increased salinity tolerance.