A pot study was made in the greenhouse using soybean cultivars Biloxi and Forrest and sub-soil samples of Dusky Red Latosol distrophic soil of four counties namely Campinas, Guaíra, Guatapará and cândido Mota of the State of São Paulo, which contained 2.9, 6.4, 11.3 and 12.9 ppm of DTPA pH 7.3 soluable Mn. The Mn toxicity was evalued 27 days after planting for visual symptoms, dry matter production of above ground parts and roots, and chemical analyses of dry matter of above ground parts. The cultivar Biloxi did not show visual symptoms at the 6.4 ppm level of Mn in the soil (Guaira) whereas Forrest showed initial symptoms of Mn toxicity at this level. As the Mn availability in the soil increased there was greater evidence of Mn toxicity symptoms and less dry matter production. The cultivar Forrest showed to be most affected by Mn toxicity which was confirmed by increase in the Mn concentration of dry matter of the above ground parts. As Forrest showed to be more efficient in the uptake of Mn from the soil and also showed visual symptoms of toxicity at low levels it can be used as an indicator of Mn in the soil. A good relationship between scores given for visual symptoms, dry matter production for the above ground parts, and the index (Mn concentration/dry matter production) shows the possibility, that scores for visual symptoms of Mn toxicity can be utilized efficiently, for screening genetic material tolerant to Mn in a soybean breeding program.