This study aims to determine high school students' reasons for mistrust of other people. In this qualitative study, the data were collected through document analysis and semi-structured interviews. The study group was selected by using the purposeful sampling method of criterion sampling. 87 students in the study group were asked to complete open-ended questions and 10 were invited for interviews. The data collection techniques in the study were the open-ended form designed by the researcher and a semi-structured interview form. The content analysis showed that students did not trust other people as everyone thinks about their own self-interest, the human nature was not reliable, people today were different, people might disappoint, it was hard to know people, people did not keep secrets, and money controlled everyone. These findings were discussed in relation to values education and the recommendations were made for educational institutions.