The genus Lilium of the tribe Tulipeae of Liliaceae is a homogenous group, showing 2n=24 chromosomes in all the species excepting L. tigrinum and L.japonicum which are triploid showing 36 chromosomes. Previously extensive works have been done by Stewart (1947), where he has shown that slight variations in chromosome morphology are associated with evolution even though chromosome number in all the taxa is constant. Though several authors (Sato 1935, 1937, Westfall 1940, Sato 1942, Noda 1966, 1967, Ohashi 1965, Ogihara 1966, Kayano 1969, Lighty and Plaisted 1960 and vide Federov 1969) worked on this genus, but work on Himalayan species of Lilium is very meagre, excepting some species growing in W. Himalayan regions (Mehra and Kachroo 1951). Therefore, extensive work has been undertaken in this laboratory through collection of species both from Eastern and Western Himalayan regions. It has been noted by the author that, chromosome polymorphism present in several populations shows that generalisations, so far made by the previous authors with regard to the chromosomal basis of speciation in Lilium, does not hold good at least with regard to Himalayan species. The present text deals with the cytological findings of eleven species and their implications in species evolution. © 1978, Japan Mendel Society, International Society of Cytology. All rights reserved.