While yolk sac tumor is one of the most common malignant germ cell tumors occurring in young children, it is rarely found in extragonadal sites. We report a case of intraocular yolk sac tumor in a 4-year-old boy. The diagnosis was confirmed by histologic examination and by the rapid normalization of serum alpha-fetoprotein level following enucleation. We propose that yolk sac cells can potentially migrate into the eye at 22 days of embryonic life during neural tube formation, when the head and tail of the neuropore open contemporaneously and communicate with the amniotic cavity.