Haematological values in 13 healthy yaks (body temp.101.1F, pulse rate 54/min, respiration 55/min) reared on winter pasture (2750m above msl; average ambient temperature -0.3 to 12.3C; humidity 30 - 100 per cent) were determined. 'Total RBC, WBC, Hb, PCV and ESR were found to be 5.20 x 10(6)/mu l, 9.9 x 10(3)/mu l, 10.2 g/dl, 25.37% and 0.54 mm/h. DLC revealed 30.0, 53.8, 10.1, 5.5 and 0.5% of neutrophils, lymphocytes, eosinophils, monocytes and basophils respectively. MCV (fl) MCH (pg) and MCHC (g/dl) were 49.3, 20.0 and 41.0 respectively.