[en] There is a potential hazard of thyroid cancer after exposure to external irradiation for the treatment of adolescent acne vulgaris. We noted a 60% incidence of thyroid carcinoma among 20 patients with such a history, who were operated on for thyroid nodules during a five-year period. Eighty-three percent of the patients with carcinoma had either a follicular or a mixed papillary-follicular carcinoma; 17% had a papillary carcinoma; 33% had regional node metastases; none had evidence of distant metastases. The interval between radiation exposure and thyroidectomy ranged from nine to 41 years. This association of thyroid neoplasms and a prior history of radiation for acne vulgaris may be coincidental and therefore remains to be proved by retrospective surveys of large numbers of treated patients with appropriate controls