A 50-year-old woman with a past medical history of steroid-dependent asthma was admitted for exacerbation of her disease. During her hospital stay, a tracheotomy was performed and a thyroid biopsy was obtained because of the purulent appearance of the thyroid gland. Histology demonstrated aspergillus. Initially the patient was euthyroid, but 3 months later she developed hypothyroidism. Thyroid antibodies were negative. There is no previous report of hypothyroidism developing in a patient with aspergillus. The patient was treated with appropriate antibiotics and L-thyroxine. Steroids were tapered down to the lowest possible dose, but hypothyroidism persisted. This case demonstrates that aspergillus can involve the thyroid gland in immunocompromised hosts and that hypothyroidism may develop.