We performed a physical examination and ultrasonography of the thyroid gland in 24 patients who had received hematopoietic stem cell transplantation with a total-body irradiation (TBI)-containing regimen during childhood. When ultrasonography revealed thyroid nodules larger than 1 cm in diameter, fine-needle aspiration biopsies were performed. Of 5 patients with palpable masses and thyroid nodules larger than 1 cm, adenomatous goiter was diagnosed in 4 cases and thyroid cancer in 1. Of the remaining 19 patients in whom no palpable mass was detected in the physical examination, 5 had thyroid nodules (including 1 adenomatous goiter), 6 had cystic lesions, and 8 exhibited no abnormalities on ultrasonography. No significant differences in sex, age at transplantation, interval between transplantation and evaluation, primary disease, preconditioning regimen, status at transplantation, stem cell source, chronic graft-versus-host disease, hypogonadism, or hypothyroidism were observed between patients with and without nodules. Individuals who received hematopoietic stem cell transplantation with a TBI-containing regimen are at risk of secondary thyroid cancer due to radiotherapy and require regular clinical evaluations of the thyroid gland by palpation, and ultrasonography should be incorporated into these checkups.