Abstract: The Taihu Lake region has a long history of cultivating rice (Oryza sativa L. sub. japonica) and has a high yield of rice. However, the genetic basis of rice varieties is becoming more and more narrow, which may result in potential risk to agricultural production. In order to enlarge the genetic basis of rice varieties by virtue of local varieties, we examined the genetic diversity of 823 varieties of japonica rice landraces from Taihu Lake region. We found that, among the 19 traits studied, the coefficient of variation of 15 quantitative traits ranged from 4.6% (seed setting rate) to 33.7% (yield per plant). There existed 10 phenotypes for husk color, 6 for apiculus color, 5 for awn type, and 4 for grain shape, respectively. For the 19 traits, the phenotypic diversity index (H′) ranged from 0.757 (grain shape) to 1.930 (filled grains per panicle), av-eraging 1.540. Phenotypic variance of accessions headed after 10 September was larger than that of acces-sions headed before 10 September (including this day). Principal component analysis showed that plant height, panicles per plant, spikelets per panicle, filled grains per panicle, spikelet density, 1,000-grain weight, yield per plant, and panicle neck length were important traits in explaining the phenotypic diversity of japon-ica rice landraces from the Taihu Lake region.