The response of six rice cultivars to aluminum toxicity was studied, in nutrient solutions using two different levels of this element (20 and 40 ppm), combined with four different salt concentrations. The tolerance was measured taking into account the root length and leaf dry weight after a growth period of ten days in nutrient solutions with Al3+ (20 and 40 ppm) combined with equal, one half, one-fifth and one-tenth of the salt concentration in a complete nutrient solution. The cultivars IAC-120, IAC-435, IAC-164 and IAC-165 were tolerant to 20 ppm of Al3+ showing no dependence of salt concentration into the solution. The cultivars IAC-899 and IR-841 were sensitive to this Al concentration when the salt levels into the solution were one-fifth and one-tenth of the complete nutrient solution. The cultivars IAC-120, IAC-435, IAC-164 and IAC-165 presented tolerance to 40 ppm of Al3+ when solutions with high salt concentrations were used. These cultivars showed less tolerance to 40mg/l of Al3+ when their plants were cultivated in one-tenth salt concentration solution. The cultivars IAC-899 and IR-841 were sensitive to 40 ppm of Al3+ and the sensitivity increased as the salt concentration of the solutions decreased. The aluminum toxicity symptoms (reduction of root growth) were dependent on the salt concentration and the amount of aluminum in the treatment solution. For the same level of Al3+ the toxicity symptoms increased with a decrease in salt concentrations in the solution for all studied cultivars, when the temperature was 30 ± 1 ºC and pH = 4.0.