Over the past three decades, there has been growing awareness and concern about the burden of ill-health experienced by men. Research has shown that fatherhood has a protective effect on men’s health but the transition to fatherhood can be complex and demanding, and may cause distress, anxiety and increased risk of depression. This article discusses paternal postnatal depression (PPND), which is a significant public health issue but is not widely acknowledged or well researched. As a result, men are under-screened, under-diagnosed and under-treated for PPND and other postnatal mental health problems, causing detrimental effects on a father’s health and numerous potential negative effects on the health and wellbeing of the mother and child.