Furuhata S et al. - This is a case report of 51 year old woman with mixed growth hormone (GH) cell-prolactin (PRL) cell pituitary adenoma is presented. She had clinical signs due to hypersecretion of GH and PRL. Resected tissue was studied immunohistochemically and morphologically. The serial sections revealed that GH and alpha-subunit were co-localized in most cells, while GH and PRL were localized in different cells.