The effect of yoga and relaxation changes in psychophysiological parameters in response to the stress of examination in 75 medical students was studied. Initially five parameters (anxiety level, heart rate, blood pressure, galvanic skin resistance and choice reaction time) were recorded, a month before the examination and on the day of examination. Students were then randomly divided into 3 group of 25 each. One group practiced yoga (Group- Y), and another group practiced relaxation (group-R) regularly for three months. The third group was control group (Group-C). All the parameters were recorded after the changes in anxiety level, heart rate, blood pressure, and galvanic skin resistance in response to stress of examination were significantly attenuated and there was significant improvement in choice reaction time in Group-Y and Group-R as compared to Group-C after yoga and relaxation.