The results of a theoretical and empirical study of basic beliefs and their relationship with the level of post-traumatic stress, personal characteristics, and psychological safety represenrarions in people with severe somatic disease ("meningioma" (n=60)) are analysed. Basic beliefs are presented as empirical markers of a person's experience of an existential experience. Hypotheses about individual psychological differences in a person's attitude to himself and the world in the conditions of experiencing a difficult life event are tested. It is proved that people with a positive attitude towards themselves and the world have high rates on the World Assumption Scale (WAS) and such subscales as benevolence of the world, controllability, justice, self-worth and luck. It is shown that a positive attitude towards oneself and the world correlates with a certain configuration of personality traits on Freiburg Personality Inventory (FPI), including sociability, poise, masculinity; the representations about psychological safety are related to the orientation of the person towards internal resources (competence, life experience, control, etc.). The people with negative attitudes towards themselves and the world, i.e. with low rates on the WAS, are characterized as neurotic, depressive, irritable, emotionally labile on FPI; their representations about psychological safety are related with the need in social support. In a group with averages on the WAS, personality profile is similar to the profile of the people with low rates on the WAS in exception of depression and femininity; the psychological safety is associated with internal and external resources. The results are discussed in the context of existential experience problem.