Cytomegalovirus (CMV) inclusions were discovered at autopsy in the thyroid follicles in five immunocompromised adults, four of whom had acquired immune deficiency syndrome (AIDS). Although reports of viral infections of the thyroid are uncommon in adults, our experience suggests that the thyroid gland may be commonly involved in patients with disseminated CMV, and the possibility exists that CMV infection of the thyroid has the potential to cause clinical dysfunction.