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Genetic diversity was analyzed with 6 632 core rice cultivars selected from 60 282 Chinese rice accessions on the basis of 12 allozyme loci, Pgil, Pgi2, Ampl, Amp2, Amp3, Amp4, Sdh1, Adh1, Est1, Est2, Est5 and Est9, by starch gel electrophoresis. Among the materials examined, 52 alleles at 12 polymorphic loci were identified, which occupied 96.3% of 54 alleles found in cultivated germplasm of O.sativa L. The number of alleles per locus ranged from 2 to 7 with an average of 4.33. The gene diversity (He) each locus varied considerably from 0.017 for Amp4 to 0.583 for Est2 with an average gene diversity (Ht) 0.271, and Shannon-Wiener index from 0.055 to 0.946 with an average of 0.468. The degree of polymorphism (DP) was in a range from 0.9 to 46.9% with an average of 21.4%. It was found that the genetic diversity in japonica (Keng) subspecies was lower in terms of alleles number, Ht and S-W index, being 91.8, 66.2 and 75.7% of indica (Hsien) one, respectively. Significant genetic differentiation between indica and japonica rice has been appeared in the loci Pgil, Amp2, Pgi2, and Est2, with higher average coefficient of genetic differentiation (Gst) 0.635, 0.626, 0.322 and 0.282, respectively. Except less allele number per locus (3.33) for modern cultivars, being 76.9% of landraces, the Ht and S-W index showed in similar between the modern cultivars and the landraces detected. In terms of allozyme, the rice cultivars in the Southwest Plateau and Central China have richer genetic diversity. The present study reveals again that Chinese cultivated rice germplasm has rich genetic diversity, showed by the allozyme allele variation.