A 9-week-old infant presented with severe postnatal hypothyroidism. His hypothyroidism corrected only after his L-thyroxine dose was progressively increased to 28 micro g/kg/d. At 6 months of age, multiple clinically asymptomatic hepatic hemangiomas were detected and support a diagnosis of consumptive hypothyroidism as a result of increased type 3 iodothyronine deiodinase activity in the hemangiomas. Coincident with the involution of the hemangiomas, the child's hypothyroidism improved and L-thyroxin replacement could be stopped at the age of 3 years. Despite some degree of hypothyroidism for several weeks during infancy, his growth and development have been normal.