Abstract: The present paper deals with the karyotype analysis of 6 species of Elymus which are native to Qinghai-Tibetan plateau. The number of somatic chromosomes in roottip cells of the 6 species and their karyotypes are reportad here for the first time, and they are all hexaploid, with 2n=6x=42. The karyotype formulae are as follows: E. melantherus, 2n=6x=42=32m+10sm, E. kengii, 2n=6x=42=34m+8sm, E grandiglumis, 2n=6x=42= 30 m+12 sm, E. laxiflorus, 2n=6x=42=32 m +10 sm, E. kokonoricus, 2n+6x=42=34 m +8 sm, E. longiglumis, 2n+6x=42=34 m+8 sm. No satellites have been founded in the 6 species and all the karyotypes belong to 1B or 2B type:

Key words: Elymus, karyotypes