The homicide-suicide is defined by any homicide (or attempt), followed by the suicide (or attempt) of the author of the facts, within a short time. The role of the addictions in these acts is not very clear and the few studies available seem to indicate a strong prevalence of alcoholism and other dependences. The authors studied eleven cases of homicide-suicide in, at least, partial bond with an addiction. The authors, survivors of these acts, were treated in units for dangerous patients. The relations between homicide-suicide and addiction seem various and rather astonishing. The complex legal aspects of these acts are detailed, with a particular glance on the responsibility for the authors of these homicides-suicides and their penal future.