With respect to the differential tolerance beyween the species, the following was observed: a) Stylosanthes and Galactia were shown to. be more tolerant. In fact, the highest dry matter production in the case of the latter took place in the presence of 5 ppm of Al; growth was not affected by the higher levels of the element. Stylosanthes did not show toxicity symptoms, maximum growth occuring in the presence of 20 ppm of Al in the nutrient soluction. b) Both glycine and Macroptilium proved to be sensitive. Lower levels of Al increased growth of the former; its dry matter yield, however, decreased when the element was given at the levels of 20 ppm. The growth of Macroptilium was reduced by 20 ppm of Al. Glycine showed toxicity symptons. especially in the root system which was seriously damaged by thehi gher Al level. c) Al additions caused decrease in the concentration of P, Ca, Mg and Mn in the roots and or in the tops. The Al of the root system was increased.