A neonate with giant-cell hepatitis developed gallbladder dilatation that was identified on ultrasonography and treated by tube cholecystostomy. Previous reports of hydrops and cholecystitis in neonates are reviewed. Ultrasound identifies gallstones and dilated bile ducts, establishes a large gallbladder as the cause of a palpable mass, and is the ideal way to follow the course of gallbladder dilatation.