A cell culture system was established in which endometrial stromal cells were embedded in a collagen matrix and separated from the endometrial epithelium by basement membrane material (Matrigel). The epithelium, seeded on top of the collagen matrix, grew in a monolayer. The cultures were evaluated by light microscopy and transmission and scanning electron microscopy. Light and transmission electron microscopy indicated a polarized columnar epithelium in monolayer with basally positioned nuclei. Scanning electron microscopy revealed a confluent epithelium with an abundance of microvilli and cilia, as well as pinopodes on the apical surface. Immunohistochemical staining for cytokeratin confirmed the epithelial origin of the surface cells, and staining for human collagen IV demonstrated its presence underneath the epithelial cells. This culture system represents a three-dimensional system that imitates the normal endometrium.