In the article, the author attempts to reveal the peculiarities of causes and prerequisites and to systematize the manifestations of ostracism of individuals or groups in the system of modern education conditions. Particular attention is paid to the analysis of the rejection system of youth and adolescence, who are previously indicated as socially problematic and are characterized by unstable self-esteem of the individual in a certain age period. The influence of the social isolation feeling in the educational space, which negatively influences the mental and physical health and success of the youth, is studied. The effects of ostracization include anxiety, depression, suicidal thoughts and tendencies, increased risk of substance abuse, and deterioration of an individual’s psychophysical health.The article is devoted to social isolation in the educational environment and its manifestations. It is pointed out that people are a social species and therefore their activity is manifested in diverse social interactions and groups. As a consequence, each individual has increased cognitive abilities to detect signals of rejection of social acceptance. Thus, rejecting from the group is a threatening situation, which is experienced as a sense of personal insecurity and leads to ostracization of the individual.The consequences of victimization from ostracism in the educational environment, such as low self-esteem, suicidal tendencies and various disturbances of the emotional-volitional sphere, fright, frustration, anger, and depression are illuminated. The practical side of individual being in the educational space is analyzed and the manifestation of intention to turn, which is part of the protective mechanism of abstinence and protects the individual from psychological pain associated with ostracism, is stated.The role of consideration of ostracization signs in the educational environment is pointed out, for their identification and prevention of an increase of the social exclusion level in the separate groups. The factors contributing to the emergence of ostracisation tendencies are considered, their division into exogenous (in the sense of belonging to a social risk group) and endogenous factors (pertaining to the personality structure of an individual) is presented.The empirical study was conducted aimed at identifying the level of ostracism and the main causes of social rejection in higher education institutions using the questionnaire «Level of social rejection in student groups», which allows tracing possible trends of ostracization.The conclusions about the causes and manifestations of ostracism in the educational environment were drawn. It was determined that the main reasons for social exclusion are unusual lifestyle, perhaps unusual appearance of the individual, as well as seclusion, shyness, low possession of self-presentation techniques, narrow circle of communication personality.Further consideration of this problem is envisaged in a more extensive study of the main influences arising from the threat of belonging, ambiguity, uncertainty of situations and denial of relations; the study of the interdependence of ostracization and the individual processes of formation in the educational group.