The application of a unit gravity cell separation procedure to rat adenohypophysial tissue is described. The results demonstrate (a) that adenohypophysial cells retain their characteristic tinctorial properties after dissociation and sedimentation, (b) that a 2–3–fold enrichment of different cell types can be achieved and (c) that the incorporation rate of labeled amino acids into the protein of dissociated versus non—dissociated adenohypophysial cells is similar. Sedimentation of cells from tissues of thyroidectomized or lactating animals yielded enriched populations of thyrotrophs and lactotrophs respectively. This cell separation technique offers a novel approach to the isolation, purification, and study of the pituitary cell types.(Endocrinology92: 265,1973)