This pilot study was undertaken in lowlanders, during their ascent from 2600 m to 3500 m, to evaluate the effects of Acetazolamide and Dexamethasone on Cardio-Respiratory parameters and Exercise Capacity. 40 un-acclimatised low-landers were divided into 2 groups. Subjects of Group 'A' were given Acetazolamide and Dexamethasone and those of Group ‘B’ were given Acetazolamide and placebo. 8 subjects matched for age, physical fitness, height and weight were randomly selected from each study group and were evaluated for their Exercise Capacities. Both study groups showed significant rise in Heart Rate, Respiratory Rate and a significant fall in Systolic Blood Pressure. There was no difference in Exercise capacities achieved by subjects of two groups at 3500 m.