Matricide is one of the rarest of reported murders and has always been considered one of the most abhorrent crimes. Psychiatric investigations as to why a son might murder his mother yield indications of a high rate of mental illness, primarily psychotic disorders, in perpetrators. In an attempt to gain an in-depth understanding of the role of the mother–son bond in the etiology of matricide by mentally disordered sons, this article presents a qualitative study of nine cases of matricide examined at two Italian Forensic Psychiatry Departments between 2005 and 2010 and retrospective analysis of forensic psychiatry reports on the offenders. Most matricides suffered from psychotic disorders, especially schizophrenia. Nevertheless, not all the perpetrators had psychotic symptoms at the time of the crime. A "pathologic" mother–son bond was found in all cases. However, mental illness is not the only variable related to matricide and, taken alone, is not enough to explain the crime. Several factors in the history of the mother and son need to be probed, especially how their relationship developed over the years. The peculiar dynamics of the mother–son relationship and the unique personalities and life experiences of both subjects are the real key to cases of matricide.