The postpartum period is associated with an increased risk of developing obsessive-compulsive disorder (OCD) in women. Postpartum onset OCD is often undiagnosed and untreated resulting in serious consequences for the patient, her family and the newborn. The symptoms of postpartum onset OCD may consist of obsessional intrusive thoughts about harming the newborn without compulsions or with both obsessions and compulsions. In this review, the phenomenology of postpartum onset OCD is described as well as strategies for screening and diagnosis. The review also characterizes the differences between postpartum onset OCD and postpartum depression and postpartum psychosis and explores strategies for managing postpartum onset OCD patients. Issues regarding pharmacologic treatment of OCD in breastfeeding mothers are also reviewed.