It is still not clear what the unique contribution of particular psychopathological factors is in explaining aggression in schizophrenia. The current study examined whether persecutory ideations, psychopathy and substance use are associated with different measures of aggressive behavior. We expected that persecutory ideations are associated with reactive aggression, and psychopathic traits are more associated with proactive aggression of inpatients. 59 inpatients with schizophrenia were included. Persecutory ideations we assessed using the Persecutory Ideation Questionnaire (PIQ), psychopathic traits with the revised version of Psychopathic Personality Inventory (PPI-R) and substance use was assessed using the Comprehensive Assessment of Symptoms and History (CASH). In addition, aggression was measured with the Reactive and Proactive Aggression Questionnaire (RPQ), in an experimental task using the Point Subtraction Aggression Paradigm (PSAP) and on the ward using the Social Dysfunction and Aggression Scale (SDAS). Results showed that psychopathy explains most of the variance in self -reported proactive and reactive aggression. In contrast, persecutory ideations explain most of the variance in observed aggression on the ward. Results implicate that it is important to acknowledge comorbid factors in patients with schizophrenia for more precise risk assessment and appropriate treatment for aggressive patients with schizophrenia. (C) 2016 Elsevier Ireland Ltd. All rights reserved.