Abstract Indonesia has lot of sub-optimal land, especially outside Java, but generally the land is acidic, contains lots of heavy metals and is poor in nutrients, making it less suitable for agriculture, including soybean cultivation. Efforts to improve land conditions through the application of liming are quite helpful, but are inefficient because they are easily washed out by rainwater and require expensive labor and costs for large areas. The use of tolerant and adaptive varieties for acidic land are effective solutions. Biosoy-1 and Biosoy-2 are new superior soybean varieties released by Ministry of Agriculture which have high yield potential (more than 3 tons/ha) and big grain, but are less adaptive to sub-optimal land so that the planting area is still limited. Efforts to improve the Biosoy variety for aluminum stress tolerant have been carried out through the introgression of the MaMt2 gene from transgenic soybean lines into the Biosoy variety. Thirty of F1 soybean seeds have been produced and 24 plants of them were positive for carrying the MaMt2 gene. Furthermore, the F1-MaMt2 plants were backcrossed to Biosoy several times in order to obtain a soybean line with high yield and tolerance to aluminum stress. Currently, a total of 16 number of BC3F1 seeds are being planting in confined screen house for molecular analysis and following by backcrossing to Biosoy-1 variety to produce BC4F1 seeds.