ErbB family members, such as epidermal growth factor receptor 1 (erbB1), erbB2, erbB3 and erbB4, are widely distributed in organ tissues, and these receptors are suspected tumorigenesis factors. We measured erbB mRNA in thyroid tissues of benign and malignant thyroid tumors or Graves' disease using Genescan. ErbB2 is associated with aggressive cancers and is used as a biological marker for the disease; Northern blot and reverse transcription-polymerase chain reaction (RT-PCR) analyses have shown it to be increased in Graves' disease. Additional studies indicated a similar result in papillary carcinoma cells; mRNAs of erbB2 and erbB3 were increased but erbB4 mRNA was decreased, suggesting distorted erbB expression may be associated with tumorigenesis. However, only erbB2 overexpression is associated with Graves' disease. These data further implicate transmembrane-type receptors in tumorigenesis in the thyroid.