Abstract: Esterase isozyme system in the seeds of Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao cultivated in Longxi county was studied by means of vertical polyacrylamide gel electrophoresis. The results showed that the individuals of A. membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao were heterogenous and the cultivated population was seriously mixed. The esterase isozyme electrophoresis used in this paper was an effective method for detecting intraspecific varities of A. membranaceus var. mongholicus

Key words: Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao, esterase isozyme, cluster analysis