Background: Violent behavior is often met in patients with mental health disorders. An important area of research studied different factors that can influence aggressive behavior in psychiatric patients. Objectives: The paper's aim was to compare different characteristics between two groups of patients, who presented with psychiatric disorders and aggressive behavior. Demographic characteristics, diagnosis, use of alcohol, history of brain injury, physical and verbal aggression were analyzed in both groups. Methods: The first group was formed of 23 mentally ill patients framed into the Article 114 Criminal Code who presented aggressive behavior and committed various offences. In the second group, 45 patients admitted at psychiatry without their consent were included, after having committed different acts of aggression. Results: The patients from the first group had significantly more psychiatric admissions in their history than the patients from the second group. A higher percentage of alcohol users was registered in the first group, compared to the second one. More patients with personality disorders and concomitant use of alcohol were present in the first group, compared to the second group. In both groups, aggressive behavior was more frequent in patients having psychotic disorders, compared to other diagnosis. Even if overall aggression was more frequent in the second group, when alcohol use (with or without brain injury) was present, aggressive behavior became more frequent in the first group. Conclusions: Results of the study suggest that when certain conditions are met, they can significantly influence the behavior of psychiatric patients, with notable differences in each group.