Increasing salinity in Mediterranean soils and the wide spread of citrus tristeza virus have challenged the use of sour orange (Citrus aurantium) and have accelerated the process of seeking alternative rootstocks. In the present study, nine cultivars of citrumelo (Citrus paradisi Macf. x Poncirus trifoliata (L.) Raf.) were evaluated for salt tolerance. Two month-old seedlings were raised under greenhouse conditions and irrigated with a half strength Hoagland solution supplemented with different concentrations of NaCl, i.e., 0 mM, 35 mM and 85 mM. Tolerance was assessed after two months of stress by measuring stem growth, number of leaves, fresh and dry weight organs and leaf water, chlorophyll and chloride contents. A differential behavior was noticed among the seedlings we studied. When using increased concentration of salt in irrigation water, all the parameters were significantly reduced except for leaf chloride content which highly increased in response to stress. At 85 mM, the cultivar SC2 showed a high tolerance resulting in less apparent leaf symptoms, higher growth and higher leaf chlorophyll content when compared to other seedlings. Similarly, the cultivar C4475-C was shown to be a strong root chloride excluder with less than 2.6% DW (dry weight) chloride accumulation at leaf level. By contrast, our results suggest that C4475-A and C4475-B are salt sensitive cultivars regarding to all the parameters studied while the other citrumelos were considered as moderately tolerant. (résumé d'auteur)