Drought is one of the abiotic stresses that reduces agricultural production in the Mediterranean basin. The selection of crop varieties with performance adapted to water stress has been the subject of numerous studies. In this context, 16 alfalfa (Medicago sativa L.) cultivars from different origins (Algeria, Australia, France, Italy, Morocco, Tunisia, and the United States) were studied under two water regimes (irrigated and rainfed) in the Lower-Cheliff plain of Algeria. The trials focused on the performance of these cultivars according to eight drought tolerance indices. To achieve this, DM yields and water use efficiency (WUE) of a 2-yr experimental study were used. Results showed a regression in mean yields from the third to the fourth year with stress indices of 0.29 and 0.88, respectively. The study of correlations showed that DM yields were well correlated to mean production (MP) and the stress tolerance index (STI). For the two trials and based on yield and STI index, ’Mamuntanas’, ’Ameristand 801S’, ’Erfoud 1’ and ’Ecotipo siciliano’ had the best performance. However, ’Coussouls’, ’Magali’, ’Prosementi’, ’Africaine’, and ’Gabes-2355’ performed poorly. Discriminant function analysis showed that the variables that discriminated in the cultivar groups for yield in the irrigated trial were modified STI, WUE, and the superiority index (Pi). The ANOVA test of cumulative yield and the regression rate confirmed that under environmental conditions similar to the Lower-Cheliff plain, ’Mamuntanas’, ’Ameristand 801S’, ’Erfoud 1’, and ’Ecotipo siciliano’ were perennial and performed under irrigated conditions while ’Erfoud 1’ performed in the rainfed trial.