Murders are one of the most important causes of mortality in Russia, and most aggressors suffer from mental disorders. The purpose of the research is to study the structure of mental disorders of murderers and its features in Chuvashia in 2011–2020. Materials and methods. The forensic psychiatric examination examined 507 murderers (409 men and 98 women) aged 15 to 83 years (average age – 40.65±13.82 years). Mental disorders, medical, social and criminal indicators of murderers, as well as 507 victims were taken into account. Results. 474 murders were committed single-handedly, 14 – in a group of 2-4 people; ordinary murders accounted for 96.5%, those with two or more victims – 3.5%. Post-homicidal suicides in aggressors were observed in 2.5%. Mental disorders were qualified in forensic psychiatric examinations in 72.6% of the subjects, most often they were alcohol dependence (20.1%), especially among women (27.6%). Among other mental disorders, personality disorders (13.8%), organic mental disorders (12.8%), schizophrenia (6.3%), mental retardation (2.8%) and comorbid mental disorders (16.8%) were noted. 10.5%, most often patients with schizophrenia and organic mental disorders, are recognized as insane during forensic psychiatric examinations. The instruments (method) of murder in 94% of cases were piercing and cutting objects, "blunt weapons" and strangulation. Women were significantly more likely to use "bladed weapons", and men – to "blunt weapons". More than 40% of the victims were family members, more than 50% were acquaintances, friends, and only 6.3% were strangers. Women were significantly more likely to kill their spouses (unmarried cohabitants etc.) and children, and men – acquaintances. 84.0% of criminals were intoxicated at the time of the murder. Both the aggressor and the victim drank together in 59% of cases. Insane murderers (with pronounced mental disorders) were significantly older, had a lower level of education, family status, hereditary burden of mental disorders, various organic harms, they killed two or more victims more often and committed post-homicidal suicides (7.5%). Conclusions. Almost three–quarters of all murderers had mental disorders, and one in five had mental disorders due to alcohol abuse. The leading cause of the murders was conflicts arising between familiar people and/or family members against the background of alcohol intoxication. A certain role was played by the criminal experience of the participants in the incident, long-term hostile relations, readiness to inflict bodily harm to the victim and murder another person.