The objective of this study was to identify factors associated with weapon use in a group of filicidal women. Clinical data were gathered from the charts of sixty filicidal women evaluated at Michigan's Center for Forensic Psychiatry or through Connecticut's Psychiatric Security Review Board from 1970 to 1996. Factors associated with weapon use were determined using chi squares, ANCOVAS, and a logistic regression. Results were compared to national statistics for child homicide from the Department of Justice Uniform Crime Reports (UCR). Weapon was defined as knife or gun for the study. Weapons were used by one of four women in our study. Guns were used by 13% of filicidal women and knives by 12%. Odds ratio showed that psychotic women were eleven times more likely to kill their child with a weapon than their non-psychotic counterparts (11.2; p = .008). Psychosis was present in every mother who killed her child with a knife and in seven of eight women who killed their children with a gun. Younger children were less likely to be killed with weapons (ANCOVA; F = 8.28; p = .006). This finding was independent of presence or absence of maternal psychosis. These results show that psychotic women are more likely than non-psychotic women to kill their children with weapons. They also show that mothers are more likely to use weapons to kill older children than younger children.