Third-trimester vaginal bleeding is a common indication for referral for ultrasound evaluation. Hemorrhage complicates up to 2 to 5% of gestations and is a major source of perinatal morbidity and mortality. This discussion focuses on the use of ultrasound to evaluate the patient who presents with third-trimester bleeding, emphasizing the sonographic diagnosis of serious obstetric causes of bleeding, such as placenta previa and placental abruption.