Abstract: Nine factors which influence the frequency of somatic embryogenesis from immature embryos of soybean were studied. The best length of immatural embryo for somatic embryogenesis was 4 mm. Embryogenesis frequency decreased as the developing stage of the donor plant increased. The best medium was MS. The efficiency of embryogenesis decreased as the sucrose concentration increased from 1.5 to 9%. Overhigh concentration of vitamin B1 was not good for the somatic embrgogenesis. The initiation efficiency of 2,4-D was superior to that of NAA, the best concentration of 2,4-D was 20 ppm. There was on interaction between light-dark treatment and the type and concentration of auxin. To a great extent, the embryogenesis was influenced by ways in which the immatural cotyledons contacted the medium. Somatic embryos produced only on the adaxial surface of the cotyledons which contacted the medium. However, when the adaxial surface contacted the medium, both surfaces couldn't produce somatic embryos. Genotypic variation in the frequency of embryogenesis was noted. However, embryogenesis was induced from all tested genotypes.