Recent work has documented the relatively high incidence of Posttraumatic Stress Disorder (PTSD) symptoms in women during the birth delivery process and afterwards, even in uncomplicated births. This phenomenon, however, has yet to be linked with cases of neonaticide (child homicide in the first 24 hr of life) or infanticide (child homicide within the 1st year of life). Women are more likely to experience mental disorder after childbirth than at any other time in their lives, and the intentional killing of an offspring by a mentally ill mother is likely underreported. The immediate postpartum period is a time of heightened vigilance by health providers and, when the tragic death of an infant occurs, forensic professionals should specifically assess for PTSD. As an illustration, the authors present a case of maternal neonaticide that was directly linked to PTSD without any other concomitant mental disorder. PTSD is a viable mitigating factor to be examined in legal defenses of infanticide either in isolation or in conjunction with other factors. (Published Abstract)