The postpartum period is associated with many adjustments to fathers that pose risks for depression. Estimates of the prevalence of paternal postpartum depression (PPD) in the first two months postpartum vary in the postpartum period from 4 to 25 percent. Paternal PPD has high comorbidity with maternal PPD and might also be associated with other postpartum psychiatric disorders. Studies so far have only used diagnostic criteria for maternal PPD to investigate paternal PPD, so there is an urgent need to study the validity of these scales for men and develop accurate diagnostic tools for paternal PPD. Paternal PPD has negative impacts on family, including increasing emotional and behavioral problems among their children (either directly or through the mother) and increasing conflicts in the marital relationship. Changes in hormones, including testosterone, estrogen, cortisol, vasopressin, and prolactin, during the postpartum period in fathers may be biological risk factors in paternal PPD. Fathers who have ecological risk factors, such as excessive stress from becoming a parent, lack of social supports for parenting, and feeling excluded from mother-infant bonding, may be more likely to develop paternal PPD. Support from their partner, educational programs, policy for paid paternal leave, as well as consideration of psychiatric care may help fathers cope with stressful experiences during the postpartum period.