Salt and drought stresses are among major constraints to rice (Oryza sativa L.) production. In order to find some keys for better understanding of the mechanism of salt tolerance in rice, we compared the impact of salinity and drought on seedlings of three rice cultivars including IR29, FL478 and Gharib, which are salt sensitive, tolerant and moderately tolerant respectively. The two days seedlings were transferred to MS media complemented with iso-osmotic concentrations of NaCl (0, 50, 100 and 150 mM) or mannitol (0, 100, 180 and 275 mM) for 10 days. Both salt and drought stresses resulted in reduction of shoot biomass, alteration of protein content and antioxidant activities in all studied cultivars. However, some isoforms of antioxidant enzymes were induced by drought and suppressed by salinity. Moreover, proline content was considerably increased only under salt treatments.