The aim of this paper is to discuss whether or not postnatal depression is a global public health concern. Public health is the study of the morbidity, mortality and the cause and course of disease, at a population rather than an individual level. Public health is also concerned with examining factors that cause health inequalities. Postnatal depression is a mental and emotional condition that can affect women during the first postnatal year. Since the effects of postnatal depression are known to go beyond the mother in that it also affects the partner and the child, it can be deemed a public health problem. Additionally, severe postnatal depression can lead to infanticide as well as maternal death, often by suicide. Furthermore, evidence demonstrates that all countries are faced with the challenge of postnatal depression, but low- to middle-income countries face the greatest burden. The literature revealed various treatment options for this complex condition. However, it also uncovered that not all women are assessed for postnatal depression, nor do all women receive treatment. The emerging picture is that postnatal depression is indeed a public health problem, particularly as the incidence is much higher than the quoted rate of 10%-15%. This paper recommends direction for public health-orientated perinatal mental health research and suggests that service providers should consider the routine assessment of all postnatal women.