Abstract: The karyotype and Ag-NORs of Macropisthodon rudis from Kunming,Yunnan Province,were examined and characterized.It had a diploid number of 46 with 16 macro- and 30 micro-chromosomes.Among the 8 macrochromosomes,Nos.6 and 8 were submetacentric,and the others telocentric or subtelocentric.A secondary constriction was observed on the long arm of the second largest pair.The fourth largest pair were determined as the sex chromosomes.Z chromosome was large,and metacentric,while the W chromosome was two thirds as long as Z and submetacentric.Ag-NORs were localized on No.2,adhering to the secondary constriction.This result differs from a previous report of samples from Japan (Nakamura,1935).Implications of taxonomy and evolution of the results were also discussed.