This article reviews the sonographic manifestations of fetal infection and the role of ultrasound in the evaluation of the fetus at risk for congenital infection. Several ultrasound findings have been associated with in utero fetal infections. For the patient with a known or suspected fetal infection, sonographic identification of characteristic abnormalities can provide useful information for counseling and perinatal management. Demonstration of such findings in the low-risk patient may serve to identify the fetus with a previously unsuspected infection. The clinician should understand the limitations of ultrasound in the prenatal diagnosis of congenital infection and discuss them with the patient.