Resistance mechanism to salinity stress is divided into two components; avoidance and tolerance. In this study, interspecific differences in resistance, avoidance and tolerance to salinity stress were examined among 12 C3 grass species. In a greenhouse, plants were exposed to 50, 100 or 200 mM of NaCl for two weeks using hydroponics system. We found that interspecific differences in resistance to salinity stress associated mainly with tolerance ability plus significant contribution of avoidance ability. Contribution of the genetic potential in the interspecific variation for resistance and tolerance was higher than that of Na+ concentration in the culture solution. Salinity stress had negative effects on shoot dry mass and water status. Relative water content correlated positively with resistance and tolerance, and negatively with avoidance. The species varied in proline content which associated positively with resistance and tolerance, and negatively with avoidance. Resistance and tolerance correlated negatively with relative growth rate and specific leaf area. These results suggested that the difference among species in resistance to salinity stress was due to both tolerance and avoidance. Proline content, relative growth rate and structural leaf properties may be used as indicators of future ability to tolerate salinity stress.