The association between low or lowering cholesterol and impulsivity, aggressive behaviors and suicide has been focused on for a long period. In the present study, cholesterol levels of the patients with borderline personality disorder in which impulsivity, aggressive behaviors and suicide attempts are clearly established have been compared with healthy controls. The study group consisted of 30 patients with borderline personality disorder according to DSM IV criteria who had applied to Fil-at University School of Medicine Department of Psychiatry and 30 healthy controls who had applied to the same center because of routine driving license examination between September2000-2001. A semi-structured clinical information form and Structured Clinical Interview for DSMIII-R for Personality Disorders (SCID-II) and Hamilton Depresyon Rating Scale (HDRS) were performed in both the patient and control group. The mean cholesterol level of patient group was significantly lower than that of controls. Likewise, the patients with current suicidal thought and the history of suicide had statistically significant lower cholesterol levels compared to the patients without suicidal thought and the history of suicide. There was no correlation between HDRS scores and serum cholesterol levels. In conclusion, the present study demonstrates that the patients with borderline personality disorder have lower cholesterol levels than healthy controls.