Background:The psychiatric assessment of individuals involved in legal proceedings had significantly been advanced during the past decades. Aim of study: To estimate the prevalence of criminal and civil problems among mentally disordered persons, identify their characteristics and determine factors that may be predictive of their responsibilities. Participants and Methods: This study was a prospective one that included 600 cases who were referred from different departments of the legal system to the forensic psychiatry unit for assessment of their criminal or civil responsibilities over 15-months duration. Data related to the cases as regarding their characteristics, diagnosis, history of illness and history of substance abuse were collected. Cases were classified into criminal and civil groups and comparison between the two groups was performed. Statistical analysis: Analysis of collected data were done by using SPSS program version 19. Results: Most of cases (86%) presented with civil problems, while 14 % of the cases presented with criminal problems. Males represented 91.7% of criminal and 61.6% of civil cases. The mean age was 33.38 years in criminal and 36.83 years in civil cases. Most of criminal and civil cases were unemployed (86.7%) and single (64.3%). High percentage of criminal cases (45.2%) were substance abusers, had history of crimes (53.6%). 42.9% of criminal cases had no social support. 48.8% of criminal cases were considered responsible for their crimes and 85.6% of civil cases were considered non-competent. There were statistically significant differences in the criminal and civil responsibilities as regarding diagnosis, severity of mental illness and 

 
degree of cognitive impairment. Conclusions: Comorbidity with substance use disorder and absence of social support are risk factors of criminal behaviour in mentally disordered persons. The criminal and civil responsibilities in mentally disordered persons are affected by the diagnosis, severity of mental illness and the degree of cognitive impairment. Recommendations: Cooperation should be established among the criminal justice, social services and medical systems to reduce criminal behaviour among persons with mental disorders through early detection, treatment, rehabilitation and reducing the incidence of substance abuse among them.