Matricide, the killing of mothers by their biological children, is a very rare event, comprising less that 2% of all U.S. homicides in which the victim-offender relationship is known. This manuscript examines more than 20 years of U.S. homicides to determine the age and gender characteristics of matricide offenders. These data reveal that most mothers are killed by their adult sons. Daughters younger than 18 years are the most infrequent killers of mothers. This article examines the incidence of parricide, the involvement of sons and daughters in matricidal incidents, and synthesizes the literature in terms of offender gender. Special attention is given to female matricide offenders, given the lack of research currently available with respect to this population. Implications for practice, policy, and research are discussed.