Abstract: Genetic diversity and differentiation in the endangered shrub Tetraena mongolica were compared with those of its relative Zygophyllum xanthoxylon from the same habitat on the western Ordos Plateau using the method of vertical polyacrylamide gel electrophonesis. Allozyme data indicated that both plant species maintained a relatively high level of genetic variation as compared with other shrubs. However the endangered shrub had lower population-level genetic variation, with P(Percentage of loci polymorphic)= 60% and 83.3%, A(Mean No. of alleles per locus) =1.6 and 2.2, He(Mean expected heterozygosity) = 0.245 and 0.392 respectively. Genetic differentiation among populations was low with Gst value being 0.051 and 0.020 respectively. These results confirm that genetic issues are not the same, nor as pressing in all endangered plants, and that conservation strategies should therefore not all be the same.