BACKGROUND The Indian Armed Forces are fighting the battle at extreme High Altitude, the most inhospitable terrain in the world, for the last thirty five years. The stress of being isolated under harsh environmental conditions on a daily basis can have an adverse effect on their mind. However, so far, no study has been undertaken to assess the psychological effects of deployment at extreme High Altitude. METHODS Three hundred thirty-four troops selected for deployment were initially evaluated using the General Health Questionnaire-12 (GHQ-12) and Armed Forces Medical College Life Events Scale (AFMC LES) as screening tools to assess mental health status after obtaining ethical clearance and informed consent. On deinduction after a deployment for more than three months, they were reassessed. The data collected were statistically analysed. RESULTS As per GHQ-12 evaluation, after the deployment score increased from 0.2574 to 0.9162, but remained lower than the 'caseness' level of 2. Among the 79 troops with a score of 2 and more, the majority were married and had past history of tenures at high-altitude areas. There was statistically significant increase in the AFMC LES scores also on deployment. CONCLUSIONS Deployment at extremely high-altitude areas for even three months produces significant psychological morbidity among troops.