The current study aimed to identify the relationships between the dark triad of personality and both traditional bullying and cyber-bullying among secondary school students, as well as finding out gender differences in all of the study variables. A total of 212 secondary school students (aging from 15 -18 years, SD= 16.61) were administered the study tools including Dark Personality Scale (SD3, Jones & Paulhus, 2014); 9 items for bullying behaviors from the Olweus Bully/Victim Questionnaire, 1996; Cyber-bullying Questionnaire (Calvete et al., 2010). Results showed that Psychopathy and Machiavellianism were positively and significantly correlated to both traditional bullying and cyber-bullying, while Narcissism was negatively correlated to them. Regression Anaysis results revealed that only psychopathy positively predicted bullying and cyber-bullying, while Narcissism negatively predicted them. No gender differences were found in traditional bullying, cyber-bullying or dark triad traits.