People learn how to behave in a specific situation. But it’s always possible to encounter new or unwanted stations which our previous experiences couldn’t be enough to overcome. Tension and pressure people feels as a result of the changes in the environment is called stress, and in today’s world stress is regarded as a part of the daily life. Avoiding exposure to environmental stressors and avoiding or minimizing other changes during periods of time require significant adaptation or readjustment. This study is about university students’ stress sources. Although there are tens of defense mechanisms, in this study, 10 best-known, or most commonly used defense mechanisms, are investigated. The research was conducted with the students taking the course of “psychology” thought by the researcher. After the researcher taught the subject of “defense mechanisms” found in the scope of this course, the students were asked to note down the defense mechanisms them “constantly”, “occasionally” and “never” used. In order to help the students remember the 10 defense mechanisms investigated, they were provided with an informative booklet explaining these defense mechanisms briefly. A total of 587 students participated in the study. The mechanisms the most frequently used especially by the female participants were “repression”, “denial” and “displacement”. The male participants’ use of the mechanism of “projection” was twice higher than the female participants’ use of the same mechanism. As for the mechanism of “sublimation”, the female participants used this mechanism with rate twice higher than the male participants. With respect to the mechanisms most frequently used, the difference between the female and male participants was found significant only for the mechanisms of “projection” and “regression”.