Abstract Worldwide chromosome number information has been compiled from the literature for monocotyledonous genera whose members have been cytologically studied in the last three years from Kangra District (Himachal Pradesh) and Kashmir (Jammu & Kashmir) in the Western Himalayas, comprising 143 species of 86 genera in 12 families, many in the family Poaceae. Chromosome number information from the literature is supplemented with new and varied reports for 54 species/56 taxa from the present study. Overall, the chromosome numbers range from 2n=10 to 2n=120. Some species in all genera show a large number of cytotypes, clearly highlighting the role of inter- and intraspecific genetic diversity as well as polyploidy and dysploidy. The basic chromosome numbers in all 86 genera are reconsidered. Monobasic genera are more common in Poaceae, and polyba-sic genera are more common in the other 11 families. Polyploidy in the different genera ranges from 3x to 40x, and is quite high in certain genera (18x in Avena, Bothriochloa, Isachne, Helictotrichon and Panicum; 19x in Saccharum; 24x in Tradescantia; 28x in Eleocharis; 32x in Cyperus; 36x in Andropogon; 38x in Poa; 40x in Dioscorea). An updated checklist of chromosome number variability in these genera is given for India and world-wide.