The diversity of chromosomes and karyotypes of the freshwater planarians,Dugesia japonica,collected from Zhanghe River of Yuecheng Town and Chaoyang Lake in Handan City,Qinwang Lake in Xingtai City of Hebei Province were studied using the air-drying method.The results showed that most cells of D.japonica collected from both Zhanghe River and Qinwang Lake had the diploid chromosome number of 16 with a karyotype formula of 2n=2x=16=16m while a small proportion showed triploid of 24 chromosomes with a karyotype formula of 2n=3x=24=24m.The percentages of diploid cells were 81.07% and 68.47%,while those of triploid cells were 8.28% and 11.71% in the two local populations,respectively.D.japonica collected from Chaoyang Lake had both the triploid(2n=3x=24=24m) and the diploid(2n=2x=16=16m) cells and their percentages made up 64.60% and 7.45%,respectively.In addition,the karyotype of D.japonica from Chaoyang Lake showed polymorphism.Based on the above results,the diversity of chromosomes and karyotypes of the D.japonica from the three places was discussed.