Whereas inguinal hernia is a common pediatric disease, fetal inguinal hernia is rarely diagnosed because intra-abdominal pressure usually occurs only after birth. We report a case of prenatal diagnosis of a scrotal mass at 35 weeks' gestation. The initial differential diagnosis included hydrocele, testicular teratoma and testicular torsion, but inguinoscrotal hernia was considered the most likely diagnosis when further ultrasound imaging using a high-frequency probe demonstrated bowel loop movements around the mesenteric artery. This diagnosis was confirmed postnatally. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.