To verify the expression and location of EGFR in pituitary corticotroph adenomas and normal pituitary glands, IHC staining was used and showed strong membrane and cytoplasmic EGFR immunoreactivity in 29 of 52 (55.8%) pituitary corticotroph adenomas and in 1 of 6 (16.6%) normal pituitary glands. This evidence concerns the gene EGFR and ACTH-producing pituitary gland adenoma.