Abstract:Chromosome numbers and karyotypes in four populations of three species in the genus Ainsliaea DC. (Asteraceae-Pertyeae) from southern China have been investigated for the first time. The chromosome number of A. henryi Diels was counted to be 2n=24, and the karyotype was formulated as 2n=16m+8sm. The number of A. trinervis Y. C. Tseng was counted to be 2n=26, and the karyotype was formulated as 2n=16m+10sm. Both populations of A. ramosa Hemsl. had 2n=26 and the karyotype of 2n=22m+4sm. In all of the populations studied the chromosomes showed a steady gradation in length from the longest to the shortest, with no evidence of bimodality. The results have confirmed the occurrence of two basic chromosome numbers, x=12 and x=13, in the genus Ainsliaea, with x=13 very likely being the primitive number.