Summary: Organ‐specific expression of a cre recombinase transgene allows for the analysis of gene function in a particular tissue or cell type. Using a 4.6 kb promoter from the mouse glycoprotein hormone α‐subunit (αGSU or Cga) gene, we have generated and characterized a line of transgenic mice that express cre recombinase in the anterior and intermediate lobes of the pituitary gland. Utilizing a cre‐responsive reporter transgene, αGSU‐cre transgene expression was detected in the pituitary primordium and in all five cell types of the adult anterior pituitary. αGSU‐cre transgene activity was also detected in the cardiac and skeletal muscle. Little or no activity was evident in the gonads, adrenal glands, brain, ventromedial hypothalamus, or kidneys. The αGSU‐cre transgenic mice characterized here will be a valuable tool for examining gene function in the pituitary gland. genesis 28:167–174, 2000. © 2000 Wiley‐Liss, Inc.