The rice cultivars IAC-165, IAC-47, IAC-25 and IAC-1246 presenting tolerance to aluminum toxicity and the cultivars IR-8, IAC-899 and CICA-4, showing sensitivity to aluminum, were crossed. The seeds in the F2 generation were obtained from the following hybrids: IAC-165 x IR-8, IR-8 x IAC-165, IAC-47 x CICA-4, CICA-4 x IAC-47, IAC-1246 x IAC-899 e IAC-25 x IAC-8. Parents and F2 seedlings were cultivated in nutrient solutions containing 10 and 30 or 40 ppm of Al3+. The length of the primary root of each genotype under study after ten days being cultivated in nutrient solution with different Al concentrations was used to evaluate the tolerance to this element. A parcial dominance was observed for aluminum sensitivity considering all F2 populations under study. No maternal effect was observed in relation to aluminum tolerance when the F2, generations from the crosses CICA-4 x IAC-47, IAC-47 x CICA-4, IAC-165 x IR-8 and IR-8 x IAC-165 were studied. Broad sense heritability stimates for aluminum tolerance expressed in root growth capacity in nutrient solutions with 10 and 30 or 40 ppm for Al3+ were high (0.497 to 0.869) for all F2 populations. These results suggested that great part of total variability found in the F2 populations for this characteristic were of genetic origin. So selection for aluminum tolerance would be effective in the first segregating generations from a cross envolving a tolerant and a sensitive cultivar. The F2 populations from the crosses IR-8 x IAC-165 and IAC-165 x IR-8 presented, as exception, very low values (0.153 to 0.193) for broad sense heritability when these populations were tested with 40 ppm of Al3+ in the nutrient solution, so 10 ppm would be the most efficient Al concentration to screen tolerance plants from F2 generations of these crosses.