Background There is no literature investigating denial of aggression in schizophrenia. Our goal was to study this phenomenon and to determine what deficits are associated with it. Methods 102 inpatients with schizophrenia were divided into three groups: (1) patients with a documented history of violent crime who denied it on extensive interviews (“deniers”); (2) those with such a history who admitted to it; and (3) those without violent crime. Patients were administered a psychometrically validated self-report scale of aggression, the Buss–Perry Aggression Questionnaire (BPAQ), the Positive and Negative Syndrome Scale and a comprehensive neurocognitive battery. They were followed for twelve weeks during which all violent incidents were recorded. Results The deniers were significantly more impaired in executive function, but not in any other cognitive domain. They did not evidence more severe psychotic symptoms or greater lack of insight in their psychosis, but this lack of insight was strongly related to hostility and suspiciousness. Their denial of aggression was also evidenced in a significantly lower self-reported BPAQ aggression score. In the patients who admitted to violent crimes, baseline BPAQ aggression score predicted subsequent aggression; in the deniers, it was negatively related to subsequent aggression. Conclusion Denial of aggression is associated with executive dysfunction which facilitates a misappraisal of the surrounding world as threatening and hostile. For those who admit to crimes, self-reported aggression predicts future aggression. In contrast, in the deniers, the extent of denial is related to future aggression. The denial itself is a marker of greater aggressive tendencies.