In the present research, which was carried out on 187 high school students (86 girls and 101 boys), we examined to what extent different aspects of social intelligence contribute to indirect and direct aggression and to what extent empathy can act as a mitigator of aggression. We used The Aggression Questionnaire to measure physical aggression, IAS-A (which includes Social Exclusion, Use of Malicious Humour and Guilt Induction sub-scales) to measure indirect aggression, TSIS (which includes Social Information Processing, Social Skills and Social Awareness sub-scales) to measure social intelligence and IRI (Perspective Taking and Empathic Concern sub-scales). The results confirmed our expectations that the cognitive aspect of empathy acts as an inhibitor of both direct and indirect aggression. The relationship between the ability of processing social information and indirect aggresssion was positive, whereas the relationship between social awareness and indirect aggression was negative, which shows that the relationships between various aspects of social intelligence and aggression are complex. People who have a high degree of social intelligence but do not have the tendency to take the other's perspective can use their abilities (especially social information processing) to performn less evident and less prosecuted forms of aggressive behaviour which still have deleterious effects on interpersonal relationships.