In order to contribute to the study of psychological adaptation to extreme environments, a discourse analysis was carried out on 10 European lowlanders during a 3-week scientific expedition under survival conditions at the top of Mount Sajama (6542 m). This discourse analysis was part of a large scientific investigation (involving 12 scientific and medical research procedures) on human adaptation to high altitude chronic hypoxia. The study of discourse was carried out on several freely delivered oral accounts on the same topic, which was always the survival experience itself. This study involved a method developed by Benzécri and Reinert which is partly described in the first part of the article. With this textual analysis technique, it was possible to determine the main word distribution patterns within a discourse and to identify the repetitive language patterns most frequently used. The results on the overall corpus, consisting of the pooled discourses, indicated three specific classes of vocabulary from which three different types of discourse were identified. The data showed that the speaker's discourse did not change during exposure to extreme environmental conditions; the discourse was not correlated with the events but referred only to the speaker himself. The three types of discourse had one main focus: the anxiety, fear or extreme fear (anguish) experienced by all the subjects as psychological states. In response to these feelings, they used various psychological strategies to escape or to face the situation in different ways, as shown by the terms of the different types of discourse. One question which arises about this discourse analysis is: what was tested when the subjects were examined with regard to their psychological acclimatization to altitude? The biological effects of severe chronic hypoxia, or those of stress in response to the fear caused by the extreme environment or/and by psychological adaptation to high altitude.