Two experiments were conducted in nutrient solution to study the level of Al necessary to separate tolerant cultivars from the susceptible. In the first experiment the levels of Al were 0, 5, 10 and 20mg/l and two cultivars Cristalina and UFV-1 were studied. These levels were found to be too high as they had drastic effect on the primary roots after 7 days of transplanting. Based on this data another experiment was conducted using 0, 1, 2 and 4mg/l of Al and using cultivars Lee, Bragg, Cristalina and UFV-1. The results showed that the length of the primary root was the best parameter as compared with dry weight of the above ground parts and roots to evaluate tolerance of soybeans to Al. The level of 1mg/l was adequate to separate the susceptible from the tolerant and the levels of 2 and 4mg/l caused drastic reduction in the length of the primary root for all cultivars tested. The cultivars Lee and Cristalina showed to be tolerant, whereas Bragg intermediate and UFV-1 was the most susceptible among the four cultivars tested.