Abstract: Camellia japonica has various ecologica,l horticultural and economical uses. An approach was establishedusing ISSR ( Inter-simple sequence repeat) molecu lar makers to c lassify and analyze the intra-specific geneticrelationship among twenty cultivars represented from C. japonica, collected in Ch ina and abroad. Twenty-onecoup les of primer sequences which cou ld amplify c learly and reproducible e lectrophoresis bandswere screened fromsixty couples of primers. Using these primers, 153 discern ib le DNA fragment were generated with 146 ( 95. 4% )being polymorphic, ind icating pronounced genetic variation at the cu ltivars leve;l the band in fingerprintingwereconverted into / 00 or / 10, where / 10 and / 00 ind icated the presence and absence of a band, respectively. Ne ipsd iversity ind ices (H ) ranged from 0. 40 to 0. 48 and Shannon. s information index ( I) ranged from 0. 57 to 0. 67.The gene differentiation coeffic ien ts ranged from 0. 5 to 0. 7 andNm ranged from 0. 2 to 0. 5. The genetic similaritycoefficients (H s) among the tested cu ltivars ranged from 0. 50 to 0. 74, averaging 0. 63. The resu lts showed that thegenetic differences among the twenty cultivars were relatively little. Comb ing the results of flowermorphology andUPGMA cluster analysis, we cou ld divide the twenty cultivars into two b ig groups. Therewere four cu ltivars in group?, which all grows in Zhejiang Province and has red flowers. There were sixteen cu ltivars in groupò, intraspec ific genetic relationsh ip comp lexity. In add ition, the results also showed that ISSRmolecu larmakerwas suitable to ana lyze the intra-specific genetic diversities and genetic relationships ofC. japonica.