Objective. The difficulties to distinguish between infanticide and murder of the woman own child, experienced by both experts and the court, have been discussed on the example of the psychopathological description of the perpetrator killing five of her children, and data from the literature. Case. This paper describes an extremely rare case of the woman who has killed five of her children immediately after their birth over several years. Comment. It is very difficult to decide whether the seemingly rational motivation to kill her own child shortly after their birth can be a proof of specific psychopathological state which is a consequence of childbirth or an assassination planned in cold blood. The act of killing a child by their own mother is so contrary to nature that it seems easy to find the ground for psychosis or a state of emergency. However, when neither of them has been proven the experts are left with the conviction of both diagnostic deficiency and inexplicability of human behaviour.