Influence of stress (cold) on visual reaction time (VRT) for red, green and yellow colours and auditory reaction time (ART) for high and low pitched sounds was studied in 60 healthy subjects (17-19 years) by digital display response time apparatus. Pain threshold and pain tolerance time were 23.02 +/- 8.11 and 249.35 +/- 64.88 sec. respectively. During the standard cold pressor test (CPT), there was significant increase (P < 0.01) in VRT for all the three colours, the increase being the least for the red colour. There was significant increase (P < 0.01) in ART for both high and low pitched sounds. There was increase in heart rate and respiratory rate as compared to controls. This increase in VRT and ART with CPT was probably due to decreased conduction velocity of nerves, which could be due to vasoconstriction attributed to increased sympathetic activity caused by cold and pain.