In order to investigate the changes and characteristics of biochemical metabolic substances of soybean tissue culture during the cultural period, immature cotyledons were detached form the plant on 15th days after flowering and cultured in vitro for 3 weeks. The cultures were classified into embryogenic(EC) and non-embryogenic callus(NEC). A part of the EC lines were subcultured for another 3 weeks and classified into root forming(RFC), and shoot forming cultures(SFC). Another part of the EC lines were used for isolation of protoplasts, which were subsequently cultured in vitro for 4 weeks. The cultures were classified into embryogenic(PEC) and non-embryogenic callus(PNEC) derived from the protoplasts. The cultures of EC and PEC lines showed higher phenylalanine content and lower methionine content than those of NEC and PNEC. At organ differentiation stage, both cultures showed the content of aspartic acid decreased, while the other amino acids increased as a whole. The protein pattern analysis of the cultures revealed that EC and NEC lines contained distinctive polypeptides, with mass of ca. 18KD for EC and ca. 22KD for NEC respectively. The EC and PEC lines also showed high activity of peroxidase isozyme A(piA), while the RFC and SFC lines showed that of peroxidase isozyme B(piB).