Present paper deals with the chromosome numbers, meiotic course and pollen viability of Cannabis sativaL., which was assessed cytologicallyin 12 populations growing in different localities of Lahaul-Spiti of Hima-chal Pradesh (H.P.) viz. Trilokinath (3,020m), Kaza (3,820m), Udaipur (2,743m), Losar (4,079m), Keylong (3,350m), Manali (2,050m), Gramphoo (3,060m), Chamba (920m), Kullu (1,362m), Khoksar (3,140m), Batal (3,960m) and Darcha (3,360m). Except, the population growing in Darcha (2n=4x=40), all the other populations were reported with diploid chromosome count of 2n=2x=20. The tetraploid (4x) meiotic chromosome count of 2n=40 in Cannabis sativaL. from cold desert area of Lahul-Spiti is reported here for the first time. Microsporogenesis was normal in most of the populations. It was present with Cytomixis (33.36%), laggards (19.52%), bridges (15.60%), chromosome stickiness (27.17%), diads (07.50%), triads (06.33%), polyads (09.50%), micronuclei and unequal daughter cells in plants of Darcha population (2n=4x=40). The consequences of these meiotic abnormalities were in the form of heterogenous sized pollen grains and low (67.33%) pollen viability